8 minutes of Counterintuitive Math

[@_shadow_1]

The birthday paradox is one of my favorite paradoxes because it feels so wrong, yet it's mathematically sound.

[@timharig]

That is because you are looking at the problem from a single person perspective. The odds you are imagining is if you pick one person and ask what is the probability that somebody in the room matches THEIR birthday. That is a different question than if ANY two people in the room have the same birthday. The same fallacy arises in the analysis of DNA evidence. An analysis usually only looks at a few dozen markers in the DNA. From this DNA matches usually quoted to have a really low number of people matching your DNA. That's true; but, it isn't the complete picture. If you instead consider how many people in large population will have matches, the number is quite a bit higher.

[@Powersd451]

Reminds me of when I told it to my mom after I learned it in school and she straight up said "That's not true, that can't be true."

[@The9thDoctor]

It's not counterintuitive, you're just thinking about it wrong. Think about it in terms of graph theory, where there is a fully connected graph with each person as a node. The probabilities that a birthday will be shared is proportional to the edge count in this graph.

[@leif1075]

​@The9thDoctor but it's wrong whether it's ckybyerintuitve or not. There's 365 or 366 days in a year..so there's no way with only 23 ppl that's the percentage of sharing same birthday without added constraints..that problem is clearly wrong..see what I mean..since for example the odds of teo ppls haring the same birthday is (1/365)(1/365) which is way less than 23 percent

[@leif1075]

@noomade my maths not wrong..of course it's 1/365*1/365 each term represents one of the two ppl..your matht is wrong 1 times 1/365 is just 1/365..did you mistyped something?

[@draketerry3497]

Every fiber of my being disagrees with p-adic numbers

[@ginnrelay]

As a computer scientist every fiber of my being does. :D

[@seejoshrun1761]

This is kind of like the infinite sum that adds up to -1/12. At no point in a finite summation would it be equal to that, but we ASSIGN the value to it. So I think it's kind of questionable to say that it EQUALS said value.

[@delayedhoe9714]

​@@seejoshrun1761Except that =-1/12 just doesn't work at all, the math behind it is deeply flawed. It just doesn't make sense

[@theeraphatsunthornwit6266]

​@@seejoshrun1761channel mathologer just disporve that like 7 years ago😂

[@starlightforever7]

Don’t worry, the whole point is that p-adic numbers don’t agree with the standard number system, it is a completely different set of rules. In our normal rules that sum would in fact equal infinity, which makes the statements given there misleading.

[@RnBrownies]

...9999 isn't equal to -1 because the two are different types of numbers Using p-adic numbers with real numbers allows you to falsely “prove” any ...nnnn = -1 conclusion, where “n” stands for a single digit. For example in the 2-adic system where numbers are written with the digits 0 and 1 (e.g. 10 = 2, 11 = 3, 100 = 4) you could show: ...1111 + 1 = 0 => ...1111 = -1 This too would be false because p-adic numbers don’t follow real number arithmetic. Rather, the problem should be written as: ...9999 + ...0001 = ...0000 ...0000 != 0

[@Moetastic]

This is the most rational answer Ive seen to this.

[@hansmikesen6355]

What's the difference between ...0001 and 1?

[@kift.]

Meh, ...0000 = 0 , lol

[@ultimatedude5686]

The way you actually solve this problem is by saying that the p-adic numbers are different from the real and complex numbers. Zero is just defined as the additive identity of a set, so ...0000 = 0. Similarly the p-adic numbers are allowed to contain one. The statement ...1111 = -1 is true in the 2-adic numbers. It's not true in the other p-adic numbers and it doesn't make sense in the reals.

[@tongpoo8985]

THANK YOU, its clickbait for people who don't know what p-adic numbers are. A more sensible answer would be 100000..., but really it just makes no sense in the context of real numbers

[@LeeDanielCrocker]

99999... = -1 because the simulation running our universe is on a twos-complement machine.

[@juliusjakas6858]

But is it a proof or only assumption? Why adding +1 you cannot write it as 9999...+1=10000.... making it 'meta' infinite? 'Surplus that goes beyond'

[@youzhou3001]

When the number is too big there’s an integer overflow!

[@juliusjakas6858]

How can infinite number be "too big". I believe in video mentioned "proof" denies that ...9999 is infinite.

[@timharig]

That was exactly my thought seeing the thumbnail.

[@timharig]

@@juliusjakas6858 When it comes to calculating machines there is no such thing as infinite. (Okay IEEE-754 does have infinities; but, that is just a signal and not useful for actual calculation.) A computer will never be able to do an infinite calculation because it will always have a finite amount of memory. This limitation can be used as an advantage. The hardware necessary to subtract numbers is also more complicated than the hardware necessary to add numbers. Adding such functionality to an adding machine or a microprocessor would take up space and require more material -- so lots of adding machines and lots of microprocessor's neglect having any subtraction hardware at all. The solution is to leverage the fixed word size of a microprocessor or the fixed number of digits of the adding machine along with the modular rollover when the size of that fix number is exceeded. Adding machine operators could do subtraction by adding ten's complement numbers and computers can subtraction by adding two's complement numbers. For a four digit ten's complement adding machine, the number -1 would be represented by 9999. If I wanted to subtract 1 from 5309, I would add the 5309 + 9999 to get (1)5308. The one that would normally be carried over to the 5th digit is simply discarded because there is no hardware to store the 5th digit. So the correct result displayed is 5308. So the joke is that if the universe is being simulated inside a computer, then any attempt to use an infinite number results in a rollover leading to glitchy results inside of the universe. Imagine a kid put ten toys into a bag and then took them out again one by one. But after he had already taken all ten toys out, he attempts to take out another toy and instead of there being no toys he takes one out and there are ...9999 toys left in the bag afterward because whoever wrote the simulation forgot to check for underruns of the counter determining how many toys were in the bag. We will not even discuss what would happen if the counter was used to index an array of toys in the bag... human sacrifice, dogs and cats living together, mass hysteria.

[@1imag337]

It's crazy how barely anyone has seen this

[@ondrejprelec527]

now that's counterintuitive math

[@TM_Makeover]

*this masterpiece

[@CatfoodChronicles6737]

Ikr

[@ioium299]

No. That is the *third* most viewed video of the channel.

[@MarloTheBlueberry]

severely underrated

[@miigon9117]

I mean a 99% water-content potato is just a glass of water with some starch sprinkled on it. So a 50% change to dry-weight really isn't too much

[@everyonelovesbabanushki]

Lmao fr

[@sonobox-lu6mr]

I always used melons in exactly this exercise: they consist of 92% water, that's close enough ;-).

[@miigon9117]

@@sonobox-lu6mr still, a -12.5% dry weight change from 92% to 91% sounds a lot more normal than the hypothetical 99% percent water potato.

[@EvanUnknown]

I don't really understand, why would the dry mass stay the same weight? It's doubled now, so would it not be 2kg? then again, I'm currently brain dead tired so idk

[@TheLifeLaVita]

@@EvanUnknownas dry mass they mean the weight the potatoes would have with no water. the total weight is always the dry mass + the water. The real statement is to find the total weight so that the total water is 98% of the total weight, not that the potatoes are 98% hydrated. It's a bit confusing (because wrongly stated) and it plays on that to look counterintuitive

[@Neubulae]

not only did you give a short introduction of proof of 0.9…=1 in just shy of 30 second, but you also explained in the RIGOROUS manner, I am impressed already.

[@allergictobs8261]

jesus died for you

[@IronSufficiency-du4sc]

and then completely botched the ...999 + 1 = 0 proof by making a false equivalency between p-adic numbers and real numbers.

[@nutronstar45]

it's not rigorous, they did not prove that there are no real numbers between 0.9 repeating and 1

[@nutronstar45]

@@allergictobs8261 unrelated

[@Sergonizer]

​​@@nutronstar45pretty sure something simple can work. Assume we have 0. To get a number with one digit after the decimal point we have to add a number from 1 to 9 and multiply by 0.1. To get as close to 1 as possible we have to use the number 9. Now we have 0.9, 0

[@coolj4334]

In a room of 367 people, there is a 100% chance that someone has the same birthday

[@xazii]

nope, what if it was a meetup for people with the same birthday? It can never be 100%

[@mwickholm]

@@xazii There are only 366 possible birthdays. With 366 people you may or may not have at least two sharing a birthday, but when you add person 367 there must be at least two people sharing a birthday according to the pigeonhole principle.

[@xazii]

@@mwickholm dang that was dumb of me. You're obviously right. That is embarrassing, I was not thinking straight when I wrote that lmao

[@YT7mc]

@@xazii With a meetup of everyone with the same birthday, I think it's safe to say that they will have the same birthday 💀 I understand the trip up, but this counter example is hilarious because literally everyone would have the same birthday.

[@xazii]

@@YT7mc yea i totally get that hahha, I prolly didnt thoroughly read the comment when I wrote that, I probably thought he said something else hahahah, that was some of the dumbest shit ive ever said tho

Missing an explanation for some of these

[@maxmustermann5590]

Absolutely beautiful how you just get to the point without wasting everyones time. If more youtubers were like that the plattform would be so much better

[@BinaryHedgehog1]

I feel like it’s a little too brief, but that’s only because I’m very interested in how the weird probabilities actually work, but I also realize that those explanations might require higher levels of math.

[@lionsblade5047]

yes

[@lionsblade5047]

this is true too@@BinaryHedgehog1

[@dazeddust8469]

The first one was a bit off but the rest this is good

[@ZiRR0]

engk wrong

[@JaffasYoutube]

The probability problem is all based on the wording, both 50% and 66% are correct depending on the wording. "Let's take the ball out of the random box, the ball is red. What is the probability that the 2nd ball in this box is also red?" This kind of setup leaves the question open to ambiguity around whether or not the ball was chosen randomly, or if just the box was. "the random box" implies the box is what was random, and 'take the ball' implies it was specific. Assuming it's all random, there a 50% chance to pick A or B. A red ball from A is 50%*50%=25%. A red from box B is 50%*100%=50%. A 75% chance total to pick a red, 25% from A, 50% from b, or 2/3, 66% that you picked box B, which will result in double reds. However, if you assume just the box was random and we chose to take the red ball first. The ball left in the box would either be Red or Not. If this ball was picked from A, there is a 0% chance the remaining ball is red. If it was picked from B, there is a 100% chance the remaining ball is red. This results in a 50% chance that the ball was from A or B. This shows the importance of being extremely clear with and direct with probability. Most of the confusion in probability comes from wording, not the maths itself.

[@shieldgenerator7]

thanks for explaining this, i knew there was some funny business going on in this problem

[@penisboss5976]

2/3 is actually never right for that problem. You ALWAYS have a red ball first, as specified in the problem, so your 25% from A 50% from B is inaccurate. It’s a given picked a red ball from box A if you at all picked from box A, so it ALWAYS has to be a green ball left. It’s a given you picked a red ball from box B if you picked from box B, so there will ALWAYS be a red ball left. The 2/3 only comes in if all balls are in one box, and you picked a red ball first. Then you now have 2/3 chance to pick another red ball, because two of the three balls remaining to be picked are red.

[@theeraphatsunthornwit6266]

I think u should not interpret it as the second scenario...i think taking a ball out of a random box is clear enough.

[@JaffasYoutube]

@@theeraphatsunthornwit6266 You have a situation where every time you look at this problem, the ball is red. It's a given. If using this form of thinking, the 50% would apply. There is also no clear distinction that the ball is random, only the box. I'm not saying I disagree with you, just that it's very important to make probability absolutely clear with no room for false interpretation, otherwise we end up with problems like this

[@fledermaus7061]

​@@theeraphatsunthornwit6266 well at least for me. I misinterpreted it exactly like in scenario two and was very confused about if I had made a mistake.

[@JustinBA007]

The periodic numbers one isn't actually true, as it is actually just a semantic argument that relies entirely on the ways we write numbers rather than the actual value itself. Sure, if you add it by continuosly getting a zero and carrying the one, you will get an infinite amount of zeros, but you'll also never finish this calculation. It'd be like if you added 1 to a hundred digits of 9s, but stopped halfway and claimed it equaled 0. If you just finished the calculation, you'd eventually get a 1 in the first digit. Same with the infinite one, just that you can never finish the calculation. Not only that, but this trick only works because we use a base 10 system, which is an arbitrary choice. If you converted the infinite 9s number to hexadecimal and added 1 to it, you would no longer get an infinite amount of 0s and would instead get something entirely different which obviously does not equal -1. Instead, this trick would work with an infinite amount of Fs in hexadecimal.

[@oLouis53]

I see what you mean but not at all the case, first they are called p-adic not periodic the p in p-adic stands for prime as these are usually used in a base with prime numbers so the number changes based on what base your in ...9999999 in 10-adic is different to ...9999 in hexadecimal. just as 10 in base 10 is different to 10 in hexadecimal. and no you wouldn't always take the result as true but certain parts of math have uses for these p-adic numbers and using these results

[@wiggles7976]

The p-adic numbers are just different mathematical objects. Veritasium did a video on them and showed how they provided a shortcut to an answer to a practical problem about the regular old real numbers that would be hard to find otherwise. I've never studied p-adics, but the idea is that you introduce a different metric on p-adics than the one you are used to so that a sequence like 9, 99, 999, 9999, 99999, ... actually has a limit just like the sequence 0.9, 0.99, 0.999, ... has a limit in the real numbers with the Euclidean metric.

[@benthomas9830]

@@oLouis53 @JustinBA007, you are both right in a sense. Whilst the actual value does indeed not equal -1 in any base for that matter if you consider it differently (like was done in the video) you can make an argument for it converging on something and it does have an actual use in mathematics. It simply depends on what rules you are using for your allowed operations. It's kind of like Fairey addition in that it isn't mathematically correct but still useful.

[@JustinBA007]

​​@@oLouis53ok, that makes sense, but that is not made clear at all in this video. The way it's presented in this video makes it sound like he is saying that an infinite number of all 9s is actually equal to -1, which is just not true in normal math. Also, not to mention that the chapter of the video is titled "periodic numbers," which only further confuses things.

[@TheMonkeystick]

This principal is actually fundamental to how computers perform arithmetic, namely how they handle subtraction by adding: Negative numbers in a computer are actually written this way, i.e. -1 is 0b11111111 for an 8-bit binary number. This means it's trivial to negate numbers (just flip all the bits and add 1) and you can just treat them like all other numbers. To give a decimal example, we can represent 1000 values with a three digit decimal number, 000 - 999. this effectively defines [501, 999] as [-499, -001] in a way that preserves addition and subtraction. For instance, 209 - 057 becomes 209 + 943, which is 1,152. Since we're stuck with three digit numbers, we drop that leading one and end up with 152 (i.e. 209 - 57)!

[@DFA_Parser]

I was thinking 0xffffffff is -1 because it's a signed integer.😂

[@raph2550]

I think that's actually not a coincidence at all

[@penguincute3564]

Isn’t that hexadecimal?

[@fahrenheit2101]

Thats actually a very similar concept.

[@DFA_Parser]

@@penguincute3564 Hexadecimal or decimal, all the numbers in computer are stored as binary. For 0xffffffff, all 32 bits in the memory is 1. If you interpret it as signed integer, then it is -1.

[@timharig]

That's precisely what I though when I saw the thumbnail.

[@NotSomeJustinWithoutAMoustache]

Bro just speedran every Vsauce2 video 💀

[@jason-anthonygaskin7867]

I feel like the ball problem may have been under specified. If I assume fungibility of the balls (eg. I don't care if I have your $1 bill or my $1 bill it's $1) then when I return to the box I'll either see red or green: Scenario 1: Balls: RG Remaining: G Scenario 2: RR Remaining: R Options: RG Probability: 50% (frequency of R/total possibilities) The 66% case would kick in if balls were not interchangeable (eg. red ball 1 , red ball 2 and red ball 3 exist) or I have the ability to pick from the other box (eg. I can pick from Box 1 even though my first pick was Box 2). I may be off here but I feel like it depends on the parameters of the problem

[@michaelshaffer0]

Just because the two balls are the same color doesnt mean they are the same ball. There are three red balls each equally likely to be picked. Picking one of the two in the same box leads to an outcome where the other ball in the box is red.

[@penisboss5976]

@@michaelshaffer0it only asked if the next ball would be red, not if it would be a specific red ball or anything. There are only two outcomes, red or green, and each outcome has a 50% chance of being true. 2/3 would only be true if the balls were all in the same box.

[@axelarnesson5066]

I agree with your statement, the probability THE NEXT BALL IS RED is 50% because it only differs in which box you picked

[@isaacwebb7918]

@@axelarnesson5066 But the odds about which box you picked from aren't 50-50, is the tricky bit. The fact you got a red ball means it's twice as likely you picked from the red-red box, because if you'd chosen from the red-green box, it's half likely you would have gotten a green ball. At first, there's a 50-50 chance you picked from either box, but getting a red ball is more information, which changes the odds. What you're thinking is that it's equally likely you picked from one of two boxes; what you really know is that it's equally likely you've found one of three red balls, and two of the red balls share a box with another red ball.

[@quentind1924]

What you are missing is that if you randomly pick the GR box, you have 50% chance to get the wrong ball, and then you might try from the ither box Start : Randomly pick option 1 or 2 Option 1 : You randomly pick the RR box (50%), you get a R ball (100%) and the other is R. So 50% to get R Option 2 : You randomly pick the RG box (50%), then you have 50% to get the R one and see that the other is G (so a total of 25%), but also 50% to get the G one, then you go back to Start So you have 50% to get RR and the other is R, 25% to get RG and randomly pick the R one and the other one is G, but on the remaining 25% you restart with a non-zero probability to then pick the RR one and get a R. So it has to be more likely to get R as the other ball Try it yourself, get 2 dices (but you have to know which one you roll) and a coin then foip the coin to pick a dice. For the first dice, whatever you roll, you note 1. For the 2nd dice, you note 6 if and only if you get a 6. Otherwise you do the coin flip again. Now, i’m pretty sure that you see how it’s rigged. It’s exaclty the same thing for the 2 balls problem

[@SkeletonKingYoutube]

The last one is tricky since the median i.e. the most common result is very different from the average if I remember correctly.

[@onecommunistboi]

The most common result would be the mode, no? And I think it is $1. The median would be a value that splits the possibilities in half: Getting a bigger payout than the median or a smaller payout both have probabability >= 0.5

[@shadowpenguin3482]

The last one is tricky because in the real world you cannot expect to win more than 100 million, so the actual value is more like 26€. After enough coin flips the lottery would just go bankrupt

[@UltraAryan10]

​@@shadowpenguin3482It will take a long time for the lottery to go bankrupt though, they can probably make it sustainable if the payment required is like greater than $5 and no one is sitting there playing 10 billion times

[@wobblyorbee279]

only 300 views? before i saw the views i really thought it has hundreds of views because the animations are just like those other good math videos with a lot of views... how can this channel also only has less than 2k subs??? it deserves more than hundreds of thousands...

[@MarloTheBlueberry]

Yeah

[@rogierownage]

You were surprised it had only 300 because you were expecting hundreds? You do know that 300 is in fact hundreds, right?

[@duck_supremacist]

The idea that an infinite string of 9s, written as "...999999999" (with an infinite number of 9s going off to the left), is equal to -1 is a speculative and controversial concept in number theory.

[@bondymagnomous3544]

A complete bullshit, to be specific.

[@kidsfree6615]

wrong.

[@cadekachelmeier7251]

It's basically the same thing as the Two's Complement format that computers often use to deal with negative numbers.

[@cadekachelmeier7251]

​@@matswessling6600where did you get ...333=-3 from? It would be -1/3. Both by doing ...999 / 3 (-1 / 3) and by doing 0 - ...6667 (0 - 1/3)

[@tfae]

p-adic numbers aren't controversial lol

[@Vastaway]

2:55 i also got 2/3 but i think the core of the problem is understanding the question. the question asks for the probability of the second ball is red WHEN the first ball is red. so the first ball can not be green this is different than a question saying: out of these 2 boxes, what is the possibility of getting two reds? then the probability wouldn't be independent of each other and would be 1/2 at least i think idk

[@jonny5955]

I got messed up on this. If we choose a random ball and we know beforehand the ball has to be red then it is 2/3, but if you choose a random ball and it just happens to be red then it's 1/2. Its like with the Monty hall problem and the 3 doors. You switch only because you knew Monty couldn't choose the door with the prize. Though, I think I may have just repeated your answer.

[@jonny5955]

Oh wait, no, I was wrong! Picking a random box then a random ball is the exact same as picking just a random ball. So if you got a red ball there's a 1/3 chance you're in the green ball box and a 2/3 chance you're in the red ball box. You have 4 equally probably events: Choose green in box A Choose red in box A Choose red in box B Choose other red in box B Doesn't matter if the green ball could be picked or not (unless both boxes were equally probable so the red ball in box A was 50% and not 25%)

[@cynx1321]

For last one it doesnt only matter how much money you are willing to pay but also how many times you are willing to play, looking at numbers best way is to play 1000 times and max money for that is 5,6$

[@Titanamyde552]

8:00 never let them know your next move: $1

[@Chomta]

Win win situation

[@Malletman2]

Why would you make implicit reference to the Archimedean property for showing 0.999 repeating is the same as 1 for the reals, and then immediately change to the 999... p-adic example, not even mentioning that the p-adics are a completely different set of numbers that don't have the Archimedean property?

[@razvanwist4185]

This is incredible. It took my teacher 4 weeks to stumble over this and you nailed it in 8 minutes. I wish professors in universities would teach like you! Just amazing!

[@Senteggo]

2:54 if you randomly choose a box with 50/50% chances, then the probability is 50%. You're talking about choosing a random ball with some magic, but to actually take a ball you need to choose a box before

[@diegonals]

Yeah but if you choose a box, there's the chance you take the green ball, which means that we shouldn't consider that occasion for the probability

[@Senteggo]

@@diegonals Well I don't remember what was in my head when I wrote this, but now after rewatching this problem I think it's really obvious why the probability is 2/3. So yeah, I was wrong.

[@benthomas9830]

This is a fun video and that's great but I do need to point out ...999 does not infact =-1 For anyone who is interested you cannot simply add one to an infinitely large number (well you actually can using ordinals but not in this case) thus to understand the value of such a number you would need to approximate it using something like an infinite series which you would find diverges to infinity.

[@canyoupoop]

Sum of all +ve naturals is -1/12 🤓

[@pashi47]

buddy they're called adics and yes .999 equals -1 in that number system, even though obviously in our "normal" number system you can't do this

[@khiemgom]

Nope this is just how padic works

[@samueldeandrade8535]

Noooooo, reeeeeally? That's why I gave this video a dislike.

[@khiemgom]

@@samueldeandrade8535 nope not rlly

[@Sr.Estroncio38]

It is a shame so little people get to see this part of maths

[@chasekwas]

For a good reason

[@smaransure2234]

lmao yes@@chasekwas

[@boochin]

True, but its practical applications are little, unless you want to go into obscure branches of statistics.

[@timharig]

They do and they frequently make bad decisions because they don't do the math. There are lots of psychological fallacies that lead to everything from bad purchases to burning money for bad investments to voting for the wrong leaders that result because of it.

[@The_Aleph_Null]

what, the part that is just trivia and funny scenarios? ew

[@StarryNightLover]

This was really mind blowing 🤯 thank you for this video i hope it gets more views

[@lighthouse6543]

I loved this video, the graphics and the subtitles really elevate the script. Youve gained a subscriber!!

[@RobloxPrompt]

Did I just see the right triangle of combinations at 7:10 which also relates to creating an input counter in circuit maker 2?! Amazing! Now rotate the x and y values so that n is the height-map for each combination and include the xor values for if numbers are only single integers. 0 would be in its own plane because we are only counting 1's here.

[@dermakol8543]

Love your videos, fun and simple - keep it up, excited to see more content from you

[@parkershaw8529]

The reason for Potato paradox to be even a paradox is because real potato doesn't have 99% of its content as water. It's hard to find some everyday food item to have 99% water, maybe diet coke.

[@hotovejmichalek7748]

This video deserves way more attention, it's great

[@cosmic8437]

This is why I hate when we put an answer down for an equation that can never be completed, 1/3 can't equal 0.3 recurring, because we can't calculate forever and saying it is 0.3 recurring is just an estimation, just like it is true for ...99999. we can't assume that adding 1 to this equals zero as we have an infinitely large 1 waiting to be put on the end of this equation, the true number it equals in 1 ...0000. as this is the best representation for this

[@danielleclement885]

1:24 potato paradox 💀

[@potatlerr]

Whats so wrong with potatoes?

[@bh4rg4v21]

But dont we add a number to the left of the decimal? unless its a decimal

[@brodyscott7132]

As a stats tutor it felt good to get most of these right haha great video !

[@zt7621]

2:12 only if you do not know the box you chose from, because it really does not matter which red you chose, but yeah if you took one from box then if you swap boxes aronud, 66-33 , but if you choose and it is red, choosing next is 50% if you scramble it will act like if it is one box anyway

[@ctanimations8488]

I may be wrong, because I'm not the best at math, but in the first paradox (the one that explains that ...9999999 = -1) the problem here is that you're assuming that this number has an end (because then you can't add 1 using the arithmetic operations, in this case addition), which is impossible because you said it yourself, the numbers are infinite. Now, EVEN if this was correct (which, like I said, it's mostly not) the moment you get at the first numbers (which are 99999...) when you add the carried 1 to the nine at the most left, you get 100000... . However, like I said, this is probably impossible, because then this number would no longer be infinite, because in the last example I gave, there IS an end.

[@shieldgenerator7]

i think youre right, ...999 does not equal -1

[@ctanimations8488]

@@shieldgenerator7 Of course, that's what a paradox is supposed to do, something contradictory, but yeah, that's why the paradox doesn't work out

[@shieldgenerator7]

@@ctanimations8488actually after learning about p-adic numbers, it turns out ...999=-1 is TRUE. It's not made clear in the video, but p-adic numbers use an entirely different math system where addition operations like that in the video are valid. in the math system we're used to, it's not valid, but in the p-adic number system, it is valid.

[@ctanimations8488]

@@shieldgenerator7 Thanks for the clarification, like I said, I'm not the best at math so this makes it much clearer. Maybe I'll investigate later about p-adic numbers, once again, thanks

[@gwilson314]

Thanks for once again showing that infinity is not a number but rather an idea. In the real (finite) world, one wouldn't have enough time to continually play the "hope I don't flip heads yet" game for anything more than a few dollars.

[@magnusbruce4051]

I'm trying to get my head around the last one. I set up a simulation in excel where it randomly picks a 0 or a 1 (my head or tail), if it's a 1 then it pays out based on the number of 0s that came beforehand. I then add up the total winnings and divide by the number of games played and it does this a million times (well slightly more: the number of rows permitted in excel). The average win per game seems to settle at around 4-5, but there are spikes where it gets really big. There's every possibility that I'm not calculating this correctly, but also I am aware that each time I'm doing this I'm working out the average win for that particular set of games rather than what happens generally. There are a ridiculous number of ways to put 0s and 1s together when you have a non-fixed number of either of them, so I guess every now and then there might be a combination that averages vastly more than what I'm seeing here. The general trend is upwards though, but when I plot game# against average win so far I see big spikes (huge wins) followed by decays.

[@ukulelevillain4170]

Yeah well basically you are never going to see the massive upside because the average wins per round grows at a logarithmic rate. You really have to look at it analytically: Expected value is the sum of all possible outcomes each multiplied by their payout. if i bet 2 dollars on a coin flip coming up heads, my expected value is (2*0.5)+(0*0.5), which is 1 dollar. Each possible outcome in our game, one more tails than the previous one, is a (1/2)^n chance of happening times a 2^n payout .Round one is a 50% chance of making 2 dollars, so that's an expected payout of 1. round two is a 25% chance of making 4 dollars, which is also one. Do you see what is happening? every round has an expected payout of 1 dollar, so when we sum them together we get a result of an infinite expected payout. Remember, the values he shows in the chart is average wins _per round_. how much money you would make is actually that times the number of rounds played. vsauce2 has a great video on this: kzbin.info/www/bejne/iHPJYqZqicamqas

[@copalo343]

I've also simulated this in python and for a million games played it only tends towards 6$ if I'm understanding the rules of the game correctly. Not sure what's wrong.

[@magnusbruce4051]

@@copalo343Sounds like you're potentially getting a similar result to me . Some of my outputs tended to around 6, but I got different results each time I ran the simulation because you do get different outcomes as every one of the 1 million coin flips I do was calculated each time I ran it. As I understand it, the longer it takes before you flip a win, the more money you get, but I'm not sure if we're considering what we ought to pay for each flip, or what we pay to flip the coin until it wins. It's possible that maybe what you need to do is consider a run of (e.g.) four losses and then a win to be one "game" and do that a million times rather than just do one million coin flips. You end up with a significantly larger dataset with a different number of coin flips each time. I'm not sure how to handle that in excel but I think I could do it in matlab as that can handle changing matrix sizes quite happily, plus I could log multiple results and see what sort of distribution the final outputs have. I have very little experience in python. This might be a task for tomorrow or wednesday.

[@copalo343]

@@magnusbruce4051 Would for sure like to see what that looks like, could you get back to me when you've done this?

[@magnusbruce4051]

@@copalo343I'll try to remember to do that if I'm successful. I'm a bit too tired to do it tonight (plus I need to install matlab for this computer) and I have a band rehearsal on tuesday night so I might not get chance to do much on it then. Realistically Wednesday is the earliest I'm going to get a chance to start work on it and I will definitely need some time to re-acquaint myself with matlab commands as I've not used it for a few years.

[@SUPABROS]

0:09 There is no number between 0.000(repeated)1, so that equals 0?

[@TheRealSusieDeltarune]

MY POINT EXACTLY, YOU CAN DO THAT INFINITELY FOR EVERY POSSIBLE CONCIEVABLE NUMBER SO AT SOME POINT IT STOPS MATTERING AND YOU CAN JUST SAY THAT EVERY NUMBER IS BASICALLY THE SAME NUMBER, ITS RIDICULOUS

[@chielvooijs2689]

The problem is that you're adding a one after repeated zeroes, that doesn't make any sense. 0.000... = 0

[@goatgamer001]

The additive persistence one is not that surprising, as the sum of the digits of a number has an additive persistance of that number -1, so for example the sum of the smallest number with an additive persistance of 3 (199) 's digits is just 19, the smallest number with an additive persistence of 2. This is true for 4 and 5, and i assume it's also true for the others as well.

[@quintonconoly]

Super underrated video. Nice job!

[@AA-100]

The one with the red and green balls is like Betrands Box paradox, where that version has a 3rd box consisting of 2 green balls. Also wouldve been cool if you did the Multiplicative Persistance as well as Additive

[@Nicomv-eu3pd]

and also kinda like the monty hall paradox, where you always change because monty hall will never reveal the door with the money, so if you change, there is 2/3 chance you win, if you dont, its 1/3, because its 1/3 chance you guessed it right first, and 2/3 you guessed wrong

[@atepomarok9339]

But 50 per cent is the correct answer.

[@Coolgirl_ig_]

@@atepomarok9339yeah your right, they did the math wrong, the probability of pulling a red ball after one red ball is 100%… not 200%, multiply, not add.

[@nutronstar45]

@@Coolgirl_ig_ it's 2/3, i suggest looking up conditional probability

[@ibrahimali3192]

@@atepomarok9339 Lets say Box 1 has 1 green and 1 red ball. Box 2 has 2 red balls. There are 4 possibilities. Box 1, green ball Box 1, red ball Box 2, red ball 1 Box 2, red ball 2 Ignore the first possibility because the given is that a red ball was taken out. 1/3 of the time its box 1, 2/3 of the time its box 2.

[@nikhilgarg9618]

Me who pays 1 dollar to play the game because it is not specified that we have to find the probability

[@SunMoonSpeedruns]

Actually, the problem with the 2 boxes is misleading. The probability of either box is equal, therefore the probability that the other one is green is 50%. The other box has a 50% chance so there are 2 possibilities of being a red ball at 25%. So to sum up: Pulling Red ball from A: 50% Pulling Red ball A from B: 25% Pulling Red ball B from B: 25% Still 50/50

[@MAML_]

The probability of box 1 is 1/3 as it is said a green ball is never drawn first, and there are 3 total red balls. With 3 possible starts there is box 1 (1/3 chance) with ball 2 being green, box 2 (1/3 chance) with ball 2 being red, and box 2 (1/3 chance) with ball 2 being red. 2/3 chance of ball 2 being red, and 1/3 chance of ball 2 being green

[@Sam-gn1db]

The probability of picking either box is equal, but you have been told that a red ball has been selected. You can draw a probability tree to visualise it. There are four possible balls at the start and after you select the first red ball, there are 2 red balls and 1 green ball remaining so the probability of picking a red ball is 2/3 since you still don’t know which box you are in.

[@endengineer2441]

Edit: Nevermind, I misunderstood the problem. Original comment: I suppose it depends on whether we assume that we have to choose the box first and then the ball or that we go straight to choosing the ball. If we have to choose the box first: 1. box A (50%) --> red ball (100%) --> 50% × 100% = 50% 2. box B (50%) --> red ball A (50%) --> 50% × 50% = 25% 3. box B (50%) --> red ball B (50%) --> 50% × 50% = 25% 1 results in green ball, so 50% chance of choosing a green ball. 2 and 3 result in red ball, so 25% + 25% = 50% chance of choosing a red ball. If we choose the ball immediately: 1. red ball from box A (33⅓%) --> 33⅓% for green ball 2. red ball A (33⅓%) --> 33⅓% for red ball 3. red ball B (33⅓%) --> 33⅓% for red ball 1 results in green ball, so 33⅓% chance of choosing a green ball. 2 and 3 result in red ball, so 33⅓% + 33⅓% = 66⅔% chance of choosing a red ball. (Sorry for any spelling or grammar mistakes I might have made, English is not my first language)

[@rya1701]

the key to this problem is that the first ball you get is always a red ball. 33% its from box a. 67% chance its from box b.

[@notwithouttext]

@@endengineer2441 for the first situation, you said the probability of picking a red ball out of box A is 100%, but it's not; there's still a green ball. it's 50%. so since the probabilities of each of them are equal (50%, 50%, 50%), then it's out of three, not out of four.

[@noobyplayz2840]

2:50 it clearly says a *random* box after taking a red ball the options are: The first possibility is it was the red ball from the first box, thats a 50% chance. the second possibility is that it was either of the balls from the second box, that is also a 50% chance.

[@Talvion-i9m]

There are only two boxes ,if you took a red ball from the first one: the probability that there is another red ball in the same box is 0% ,in the second box: if you take a red ball the probability that there is another red ball in the same box is 100% , so the total probability when you are picking random will be 100+0/2 = 50% , am I stupid or most of the things in this video doesn't make sense

[@james-h2w]

When you pick a box at random and you get a red ball you now know that it’s twice as likely you had picked from the box that had 2 reds, this means the chance your next ball will be red is twice as likely as it being green, we also know the probability of these two scenarios should add to 100% because they are the only two, you can write this as p + 0.5p = 1 P = 2/3

[@MrMichalXXL]

Actually if you have 9999... repeating and add one it doesn't give you 0 since there is (at least in some sense) 1. The fact that you cannot reach the end (or like in this case beginning) of it doesn't mean it doesn't exist so its both logical and mathematical error

[@xSchockZz]

True for our normal number system we use. In this case we were in a p- adic system . It has a different definition.

[@jfWm_Py.-41-dVsVTISy6g5x.W3--U]

you can't reach the end because there isn't one. the sequence is infinite by definition

[@efisgpr]

The probability that the second ball is red: Case 1: you took it from box A 0% chance Case 2: you took it from box B 100% chance "What is the probability that the second ball in this box is also red?" 50%

[@jwjustjwgd]

Case 1: you took the only red ball from box A Case 2: you took one of the red balls from box B Case 3: you took the other red ball from box B You can get actual boxes and balls and do the experiment yourself (have someone else randomize them or use your own system to,) and the other ball will be red 2/3rds of the time. I tried it myself.

[@theeraphatsunthornwit6266]

Before you pick, the chance of picking a box is 50:50, but after you get a red, now with this new information, the chance has changed. Same like you can teleport randomly anywhere in the world with equal chance, now u teleport, you see an arab, what is the chance that u teleport to an arab country

[@maniacpwnageking]

You're wrong on a couple of these, at least as your presented them. The way your providing the information is not the same as wherever you took these problems from.

[@williamwalsh4743]

Sources plz

[@maniacpwnageking]

@@williamwalsh4743 I typed out a whole explanation already, and then accidentally deleted it. The potatoe one seemed off, but I'm not sure about that one. The red ball green ball one is wrong fs. Without further specification, it makes most sense that you would be randomly choosing a box, and then randomly selecting a ball from within. The way he calculated assumed that you have an equal probability of drawing every ball from either box, which is not true.

[@sirk603]

@@maniacpwnageking1. The potato one is fine. The dry mass stays the same, so it should always have 1 kg, work from there. 2. The ball one isn’t wrong. He just said you randomly choose a red ball, why would you assume that he first randomly chooses a box? That’s your assumption which you have chosen to make.

[@vp_arth]

Sometimes(p=1/4), you will get green ball and skip that. When you get red(p=3/4) you, obviously, have 1 outcome to get next green and 2 to get next red.

[@percyjackson5017]

You need to include 1+2+3+4+......= -1/12 (and sometimes -1/8). This video was AMAZING. i need a full series of this. This gave so much vsauce vibes

[@lightbearer313]

Mathologer did a good video on this: kzbin.info/www/bejne/j6asep2Cp5upi6M

[@UltraAryan10]

Well that sum is not counterintuitive, its just not true. It has to be true and proven in order to be counterintuitive.

[@RuthvenMurgatroyd]

​@@UltraAryan10 You can make the same argument about n-adics here.

[@UltraAryan10]

@@RuthvenMurgatroyd P-adics can be treated as a different branch of numbers seperate from real numbers. This sum, people try to put into natural numbers set and thats just not true.

[@RuthvenMurgatroyd]

@@UltraAryan10 the sum can be defined mathematically just like ...999999 is my point even though both are divergent and have no _real_ meaning.

[@scientistsingh3695]

Please keep uploading such videos ❤

[@pragyanpranay3681]

Also matching problems are just dearrangements? And then the formula of derrangements just converge to 1/e as the sum goes to infinity!

[@bananarepublic3440]

Actually, if you played that game an infinite number of times, you would lose exactly $1/12

[@thomassynths]

You would die well before that. So there is indeed a finite bound to any expected reward.

[@theeraphatsunthornwit6266]

This is a joke/sarcasm to the mistaken proof that infinity = -1/12

[@lagelk2000]

I love this channel so much, I hope you get popular soon!

[@bobbiesaids4795]

0:40 p what?

[@md.tahseenraza4791]

p- adic

[@YT7mc]

"p, in fact" is what he's saying

[@JakubS]

When you said "P, in fact," I thought for a second that you said "being f*cked"

[@jonajon91]

Had to stop watching this because I was getting angry.

[@flameofthephoenix8395]

Infinite 9s repeating plus one isn't just 0, there is a carry of one after all infinite nines, so I would describe it as 1 with infinite 0s afterwards, no different than 1.0 repeating multiplied by ten to the power of infinity.

[@andrewdevlin8756]

Yeah, pretty stupid math. Obviously not equal to -1.

[@HaydenNK3]

While I do agree with you, I think the point was to say that since you can never reach the last 9 to make a 1 (maybe calling it the first 9 would be more accurate), it's like putting a bunch of 0's until the end of time and beyond. Therefore, the sum is 0, making the number -1. To me it's just a matter of how you look at it. Because you can think about it the way you did and make it exactly what you said "1.0 repeating multiplied by ten to the power of infinity" I personally find it more logical "your" way

[@Slackow]

This is not actually the case, because you can't actually represent a number that way, because the 1 has no position. Any digit you ask about is 0. So the result is actually 0. It forms a completely coherent number system for it to work like this even if it's a little counter intuitive.

[@skellq4385]

@@andrewdevlin8756Look at the title

[@skellq4385]

@@SlackowYes. These 5th graders are finally understanding what math is. Wait until they get to 0th power.

[@Nzargnalphabet]

At 366 people if you don’t include people with leap years, the probability is exactly 100% due to the pigeonhole principle

[@b1oodzy]

The ball one doesn't make sense though. There are 3 outcomes but 2 of the outcomes are combined as 1 since they're both red balls. (Nvm I understand now)

[@youtubeuser.1]

I wouldn't say combined but I agree with you because the 3 outcomes which he mentioned (and thus used to conlude a probability of 1/3) are not equiprobable if he chose a random *box*

[@johnbyrnes6621]

you may be combining them, but that is actually wrong. Imagine you also number the balls. Clearly, you have a 25% chance for pulling each ball. Keeping the numbers, there are 3 numbers that result in pulling a red (let's say 2,3,4). Each of these is equally likely, so 1/3 each. Now, of the set (2,3,4), how many are from box B?

[@b1oodzy]

@@johnbyrnes6621 Ohh wait yea I understand, 1/3 is green and 2/3 is red. So that's 33% and 67%.

[@youtubeuser.1]

Nvm I was wrong. Here is the python code that I wrote, feel free to point out any logical errors import random redcount = 0 greencount = 0 remainderoftrials = 0 for i in range(10000): initialboxchoice = random.randint(1,2) box1 = ['g','r'] box2 = ['r','r'] if initialboxchoice == 1: removed = box1.pop(random.randint(0,1)) chosenbox = box1 else: removed = box2.pop(random.randint(0,1)) chosenbox = box2 if removed != 'g': if chosenbox == ['r']: redcount+=1 elif chosenbox == ['g']: greencount+=1 else: print('ERROR') else: remainderoftrials+=1 print(f"Other ball was green: {greencount}") print(f"Other ball was red: {redcount}") print(f"Remainder of trials, i.e. those where the first ball was green: {remainderoftrials}") print(f"Experimental probability that the second ball in that box was also red: {redcount/(redcount+greencount)}") P.S. Ik that the code could be written much better, I just wanted to make super sure that it was error free Conclusion: Probability = 2/3

[@theeraphatsunthornwit6266]

Hmm...no. The question ask.. what is the chance of another ball in the box you just chosen is red. It does not ask you to choose a ball from the remaining 3 balls.

[@milckacow1230]

the potato paradox is wrong, if 1% dry mass = 1kg, 2% dry mass isn t 1kg, because 1% of water evaporates, it means it s more dry mass, because if it t less water, the potate is more "dryer"

[@martind2520]

The term "dry mass" is refering to the mass of the object that is made out of molecules other than H2O. That is not going to change as the water evaporates.

[@RTOmega]

No views? Lets fix that!

[@pragyanpranay3681]

Probability Problems like box one can be fixed quite easily with Bayesian thinking! Although its not very natural to think of them when sample space is very small... So, it gets very paradoxical.. I think the ball problem is equivalent to monty hall problem?

[@nazu.roblox]

1:08 There is a 1 leading all the zeros

[@ginnrelay]

No there isn't, because there is no "start" to the number.

[@elena.krittik]

Great vid! However, i don't get why there must be something between two numbers for these numbers to count as "different". Is that some axiom i'm not aware of?

[@andrewfontecchio6257]

Agreed. The point of saying greater or less than means you know the values of the numbers and you compare them. If I had a number line with just the integers then could I say that because I cannot fit a number between 4 and 5 then they are the same number? No. By this logic every number would have the same value.

[@martind2520]

In the real numbers, if x and y are distinct, then there always exists a third number that is (x + y)/2.

[@elena.krittik]

@@martind2520 Thanks for bringing this up. @andrewfontecchio6257 I just found this en.m.wikipedia.org/wiki/0.999... An interesting read.

[@kerr354]

yes there seems to be such an axiom. The trichotomy of the reals. For any pair of real numbers either x=y, xy holds. Assume x

[@un-known2204]

U deserve more subs this is just free knowledge 🔥🔥❤️

[@Vastaway]

2:06 can someone explain? wouldn't the second case be: m = 100kg water = 98 kg dry mass = 2 kg am i misunderstanding the problem?

[@hexagon7638]

nope

[@harveybriggs7729]

The dry mass can't go up I think?

[@ChlorinightS]

It's dividing its a little weird but 99% water = 99kg 1% dry = 1kg *2%* dry =1kg(as usual) that mean 98% = 98/2 = 49kg it doesn't even make sense for me but that's how I got the answer

[@RanDom-if2ee]

​@@ChlorinightSThank you. I can't understand it, but thank you.

[@Kero-zc5tc]

Measure everything by the dry mass. The dry mass is constant and is 1kg in the 99% potato and In the 98% potato it is still 1kg of dry mass but this time is 2% of the potato. The reason this is hard to grasp is people don’t realise percentage is a ratio

[@sand_is_op5754]

something similar is that the percent of children who are single children is significantly lower than the percent of parents who have a single child (provided the avg children per parents is above 1)

[@The21stGamer]

Did they count each individual parent separately?

[@theeraphatsunthornwit6266]

Intersting. Never heard this b4 Oh i get it why. Even a pair of parents is counted as one. Imagine an exaggerated village with 2 pair of parent One parent has 1 children One parent has 100 children When computed as ratio, you are one child in a 101 child that is single

[@weakw1ll]

1:00 kinda like saying infinity and 0 have similar values

[@Dosor72]

Yes, things are counterintuitive when you explain the problem in a misleading way

[@james-h2w]

I thought the assignment paper one would be 9/10* 8/9 * 7/8 * 6/7 * 5/6 * 5/5 * 4/4 * 3/3 * 2/2 * 1/1. The last 5 fractions being 100% because their papers have to be gone by that point and it comes out as 50% can someone let me know how this is wrong

[@bananapalmtree8445]

for the probability problem, It stated that you're taking a ball out of a random box and that the ball is red. If you took the red ball from box A then the next ball is green. If you took the red ball from box B the next ball from the same box is red so it should be 50-50. You stated that we take a red ball out of a random box. The two options are taking a red ball from box A or from box B since you're randomly choosing the box that you choose. I'm kinda confused tbh. edit: I now realize where I was wrong

[@water_offire4892]

It's conditional probability, doesn't make much sense at first but if you want to learn more, you can check bayes' theorem. For this problem, the question is "what is the probability that the other ball is red if the first is also red" which can be written as P(R2 | R1) with R1 : "the first ball is red" and R2 : "the second ball is red". You can calculate each probability separately but using a tree like shown in the video is way more intuitive and easy for this case (correct me if i'm wrong)

[@dominobuilder100]

I agree. It should be 50%. He said ”a random box” so it’s 50/50 which box he chooses. If he had said ”a random ball from these two boxes” it’s another story. It’s super important to be clear about these things when handling probability.

[@Ayzev]

​​​​@@dominobuilder100It's 66% because of the part where you already took one ball out and know that it's red. The 2 red box is more likely than 1 red 1 green to get you a red ball first, hence getting red first makes it probable that you picked the 2 red box.

[@loganblakely3448]

No each ball in box b is 25% box b has only red balls so that's 100% which is 50%. Of both boxes. There is only 1 red ball in box a and the chance that you picked it first assuming you got a red ball first and chose box a is 100% and the other ball in there is 100% green so 0% that both balls in box a are red and 50% + 0% is 50% boom.

[@Ayzev]

@@loganblakely3448 2/4 chance that you pick the box with 2 reds and get a red ball, and 1/4 chance that you pick the 1 green 1 red box and get a red ball, and 1/4 chance of getting the green ball. You got a red ball, so the case where you get a green is now excluded. You're left with the 2/4 of the 2 reds box, and the 1/4 of the red green box. That's how we get the 2:1 chance, or 66%

[@technofeeling2462]

The last one is weird. If there is a fixed expected value why would the average win grow with attempts? I mean it was like looking for the average win of a lotto ticket and the same thing happens. OK it's at night and I am super tired. Maybe I look at it again tomorrow.

[@VRS-hj6ep]

Because it only goes to infinity when you take into account extremely rare events, 20 flips until heads for example gives 2^20 dollars but also has a probability of 1/2^20, and the more simulations the more likely to get those.

[@phyllipkjellberg7160]

0:32 So that means ...9999.9999... = 0 🥴

[@timurkucherenko2138]

huh

[@TotallyNotJ4denn]

I understand because if .9999… = 1, and 9999… = -1 Then adding these results in …9999.9999… or -1 + 1

[@Talvion-i9m]

The potato paradox is absolutely wrong because you need to have a constant to the mass of the potatoes , we aren't talking with ratios

[@Talvion-i9m]

I just don't understand why in the potato paradox we use the dry mass as the constant it doesn't make since in the real world

[@asialsky]

Now do the part where ...9999999 is also _not_ equal to -1, as you can subtract 1 and get ...9999998, not -2.

[@tintenfisch3421]

...999998 + 2 = 0, therefore ...999998 = -2

[@ginnrelay]

But ...99999998 *is* equal to -2.

[@vindifrenzy1100]

I learned way more interesting math than in school! You need more subs! You are so underrated! Please make more videos I really enjoy them! I just subbed to you and turned on all notifications!

[@Eichro]

The ...999 example doesn't convince me at all. If you add 1 to it, you'd have an 1 after the infinite 000s. So it'd be more a 1...000 thing rather than a 0, and if there's no mathematical notation for it, blame mathematicians, not me. Next time you're gonna tell me that summing all integers gives us -1/12.

[@ronflypotato4242]

I can answer that for you, but still take in count I could be wrong you may say that that number is infinity since that number is the sum of infinite non-converge geomtric series. (9+90+900+9000...) which makes sense with why you can't just simply add one into it and ask what is the number's representation in decimal base. from the statement of the video that this number is equall to -1 ( if this statement was true..) we could construct a proof by contradiction that this number does not exist by saying that a number is equall to -1, we already asumed that he does exist we can easily say that 9+90+900 is bigger that 1 we get x>1 and x=-1 , a contradiction therefore x does not exist.

[@ronflypotato4242]

Also there is a similar thing going on with the sum of all integers gives us -1/12 (if it was true) we already know that 1+2+3... is bigger than one which gives us a contradiction but I have a question is infinity a number? or can we say infinity exists?

[@YT7mc]

@@ronflypotato4242 9 plus any number of positive ints will remain greater than 0, -1 is less than 0, (aka ...999 > 0 > -1), ...999 = -1 contradicts this. This is the same as your proof, right?

[@JustinBA007]

Yeah, the argument in the video seems like just semantics imo. Like, sure, if you do the addition manually and carry the one you get an infinite number of 0s, but that's just a consequence of the way we write numbers. That doesn't make the actual value -1.

[@notwithouttext]

yeah i used to believe "adding the natural numbers gives us -1/12" but it's more like "adding the natural numbers would diverge and not have a value, but if we extrapolated from other results we'd get -1/12"

[@xcy7]

I don't agree with the boxes ones. You pick a box and you're guaranteed a red ball. So the problem becomes whether you picked the box with 2 red balls or not: 50/50. For the record, I do understand Monty Hall and I don't think there's a connection to it like some comments suggest. In Monty hall you get additional information and the option to modify your choice, here you don't get anything. Your initial 50/50 choice dictates if your second ball (from the same box) is red or green.

[@ffbotha]

No, the boxes one is correct. You're right in that your chance to draw two red balls is 50%. It's just that the additional information the question gives you says that you're in a subset that only happens 75% of the time (the *first* ball you draw is red). So the chance of the second ball being red, given that the first one was red, is 50%/75%, or 2/3 (which I think would also have been a much more intuitive way of visually demonstrating it in the video). I agree that this isn't connected to Monty Hall though. That's an entirely different issue.

[@xcy7]

@@ffbotha Ah. I think i misinterpreted the problem. My assumption was that the first ball is guaranteed to be red. But yes of course, if the first ball being red is a probability, then it's correct.

[@meijuta]

i literally had the idea of the thumbnail one this morning, i had never even heard of p-adic numbers and now im following a rabbit hole. ty 4 dat

[@ThombTjing]

I hope we can come to grasp the concept of infinity better in the future, it is a really prominent one in the universe and thus could be really helpful in understanding it and how it word. Which in turn could help us advance as a civilization further (hopefully leading to human domination of the universe).

[@stevenvanhulle7242]

0:05 Your visual proof that 0.9999... = 1 seems to be circular, i.e. you use your premise to prove your premise. A more common proof goes like this: Let x = 0.99999... Then 10 x = 9.99999... Then 10 x = 9 + x Then 9 x = 9 Therefore x = 1 Ergo 0.99999.... = 1 QED

[@masscreationbroadcasts]

Here's a fun demonstration. For a number x of length k, the periodic number 0.(x) = x/99...9 where there are k values of 9. Try it yourself. Therefore 0.(9) = 9/9 = 1. P.S. A demonstration for that formula is that 10^k * 0.(x) = x.(x) = x + 0.(x) So (10^k - 1) * 0.(x) = x 0.(x) = x/(10^k -1) = x/99...9 where 9 is repeated k times.

[@shieldgenerator7]

thats a neat fact!

[@quentind1924]

0.(9) isn’t in the P-adic system. ...999 is not the same thing than 0.999... at all

[@shieldgenerator7]

@@quentind1924they werent talking about p-adic numbers at all

[@quentind1924]

@@shieldgenerator7 It’s literally written during the entirety of it

[@shieldgenerator7]

@@quentind1924 i dont understand why you think @masscreationbroadcasts is talking about p-adic numbers

[@SlamWeasel]

The periodic number doesn't make sense tho 0:34 You say, ...999 + 1 = 0, but that can't be, because, as you said, it gives us a 1 with infinite 0s. But we can paraphrase that A 1 with infinite 0s is basically just 1×(10^inf) or just 10^inf. Meanwhile, 0 would be 10^(-inf) 10^inf ≠ 10^(-inf) therefore ...999 + 1 ≠ 0

[@martind2520]

p-adic, not periodic.

[@SlamWeasel]

@@martind2520 if that's all you have to correct, then I suppose you agree with my mathematical proof

[@martind2520]

@@SlamWeasel No, not at all. Most of what you said had absolutely zero mathematical rigour whatsoever. I just gave you the correct name so you could research the topic for yourself and find out how the p-adic numbers actually work.

[@SlamWeasel]

@@martind2520 So a number consisting of a 1 with infinite 0s is not equal to 10^infinity? A decreasing exponent does not make the result tend towards 0?

[@martind2520]

@@SlamWeasel There is no such number as something with a 1 followed by infinite 0s. Infinity is, by definition, unending, you are trying to put a 1 at the left of those 0s which are unending to the left. That is a contradiction. So no, it is not equal to 10^infinity, as it doesn't even exist to be equal to that.

[@hexagon7638]

0:56 Yes but there is a one at the start :/

[@sahil04925]

1:00 But there must be a 1 at the left most position. So the number plus 1 is 10 to the power infinite and not zero.

[@quentind1924]

Where is the 1 then ? Infinity, for definition, you can’t put anything "after" an infinite amount of anything, so you try to put something at a place that, by definition, doesn’t exists But P-adic numbers is a different number system, i agree on that part. 9+90+900+... is equal to infinity, unless you are talking in the P-adic system

[@sahil04925]

I am not good at maths, so I guess this is what you mean: We put the number 1 after infinite places, so we will never reach the number one, therefore the number 1 is simply not there. @@quentind1924

[@MetaphoricMinds]

Ok, at 2:09, what if it was dehydrated to 97 percent. Would it then be 25kg, and keep halving?

[@theeraphatsunthornwit6266]

No, you just need to solve the equation 0.97 = x / (x +1) X = 32.333

[@quentind1924]

​@@theeraphatsunthornwit626633.333...kg* But yes, it’s one third

[@JuanPretorius]

0.9 recurring is equal to itself

[@martind2520]

Yes and it is also equal to 1.

[@jeano7684]

the anwser to the probability problem is 50%, the balls from the second box cannot travel into your chosen box via osmosis, so you only have a single ball that is either red or green, not three balls that are red, red, and green

You picked a ball randomly and it was red. Given this, three cases are possible: • You picked the red ball from box A. (The next ball will not be red) • You picked ball 1 from box B. (The next ball will be red) • You picked ball 2 from box B. (The next ball will be red) 2/3 of the cases are valid for our conditions. Probability is 2/3. It is not 50% because the probability of picking a red ball from box B is higher than that of box A.

[@Ayzev]

The chance of the first ball being red is higher if the box you picked is the one with 2 reds. That's why it isn't 50%

[@piadas804]

Slab amogus

[@technofeeling2462]

I think if you make that example with people and the color is represented by gender it's easier for you

[@jwjustjwgd]

Just do to experiment yourself and get 2/3, it's not hard to set up

[@shalazoo8806]

But when water evaporates aren'tyou making dry mass?

[@welcometochiles6156]

_ 9 + 2 9+2 = 1 c1 9+2+1 = 21 c1 _ 9 = -1 _ 9 + 2 = 21 -1 = 21 Nah. Something ain't right.

[@broxrosenfeld8418]

I got the red ball problem right! I think it's the same principle as the Monty Hall problem.

[@yudikubota293]

This video has the perfect length for a snack

[@DaylenAmell]

To say that 0.999...=1, you have to be a little more careful. It's easy to show that the largest number that is possibly smaller than 1 is 0.999..., and hence either 0.999...=1 xor there are no numbers between 0.999... and 1 (and 0.999... is smaller than 1). But to show that it must be 1, you still have to use e.g. that the set of real numbers is dense - there cannot be no numbers between any two real numbers. Of course, you can also easily sum the infintie series of 0.9+0.09+0.009+... as it is a geometric series. After seeing the last expected outcome game, I noticed another way to find 0.999...=1 using probability calculus. Note that { the sum over all positive integers n of [the probability of getting the first head at the nth toss] } must be 1, since in each game [you must get the first head at the nth time for some positive integer n if you do end up getting a head] AND [the chance that you never get a head is limit n goes to infinity of (1/2)^n, which is 0], and summing over the probabilities of all [the possibilities of non-zero probabilities] must yield 1. And this probability sum is also a geometric series 1/2 + (1/2)^2+(1/2)^3+..., so this example tells us that you can make an exact analogy between the probability sum and the geometric series. For the series 0.9+0.99+0.999+... = the sum over all positive integers n of 9/10^n, let's consider a random number generator that generates all numbers from 0 to 9 with equal probability - let x be an arbitrary number from 0 to 9, then the probability of getting [any number that isn't x] for the first time after using the generator exactly n times would be 9/10^n. As before in the expected outcome game, { the sum over all positive integers n of the probability of getting [any number that isn't x] for the first time after using the generator exactly n times] } must be 1 by probability calculus, and must also be equal to the sum over all positive integers n of 9/10^n, and hence we obtain 0.999... =1.

[@TM_Makeover]

Full support 🎉🎉🎉

[@voidmarvin]

...999+1 shouldn't be 0 Instead, ...999+1 = 1...000 (Doesnt 1 get carried to the end?)

[@penguincute3564]

2:10 Box A and Box B: 50% + 50% Red ball in Box A: 50% Red ball in Box B: 50% + 50% Red ball from Box A: 25% Red ball from Box B: 50% Chance of taking out an red ball: 25% + 50% = 75%

[@jaydenh5748]

You didnt account for the assumption that the first ball was already taken out and found to be red. This eliminates the possibility of drawing the green ball first, so it goes from 3/4 to 2/3.

[@quentind1924]

I roll a dice, i see the result and i say that it’s smaller or equal to 4 (and i can’t lie. If you don’t trust me then we do it with a dice that makes a very loud sound when it rolls 5 or 6, and you heard nothing. That way, you can be sure that it is smaller or equal to 4). What’s the probability that it’s a 1 ? With the ball puzzle, it’s the same thing : Box A + box B = 50%+50%. Box B red ball A 25% (other one is red), box B red ball B 25% (other one is red), box B red ball 25% (other one is green). And box a green ball 25% but you see that it’s a green ball so it doesn’t work therefore you discard it and it’s 0% Yes, now you only have 75% of anything, but let’s say that on the remaining 25% you reset which leads to all 3 scenarios with equiprobability. So it’s 33% to get box A red ball (other one is green), 33% to get box B red ball 1 (other one is red) and 33% to get box B red ball 2 (other one is red). So ⅔ to have the other one be red

[@rojastegulu]

Bro really said 99% of gambling addicts quit before they hit big 💀

[@starblox0983]

Since we picked a red ball, we minus the balls and we are left with 2 red balls. 1 of which were in the same box we were in. So by using the formula for probability: desired/total we get 1/2 which is 50%.

[@JackieJKENVtuber]

0:15 we can't put a number between then because 0.(9) is the real number right before 1. You can put 0.(9)9 between 0.(9)8 and 1, but that's the only number you can fit between them It's like 1- and 1+ in limits - they represent the numbers approaching 1 from both sides right up until 0.(9)9 and 1.(0)1, but neither are 1 and I'm so tired of people pretending they're the same without approximation. Here's a counterpoint: 0.(9)9 = 1, therefore 0.(9)8 = 0.(9)9 = 1 because you can't fit any numbers between 0.(9)8 and 0.(9)9, and we've "proved" that's equal to 1. If you keep repeating this infinitely, you will reach the conclusion that every real number is equal to 1, which is obviously untrue. The p-adic number is also bullcrap. Since we're dealing with an infinite number of 9s - which can be represented as 9(9), once we add 1 we will have 10(0), not (0). There will be a 1 infinitely to the left. Only seeing the 0s like you telling me that there's no number over 255 because you can't store the number 256 in 8 bits. Yeah, you can't store or view 256 with only 8 bits, but that doesn't mean 255+1=0, it just means that you'll need more than 8 bits to see it

[@jwjustjwgd]

0.(9)9 and 0.(9)8? There is no digit at the end of infinitely many digits, there is no end. 0.(9) is 0.(9)

[@JackieJKENVtuber]

@@jwjustjwgd 0.(9) = 0.(9)9 There must be a last digit infinitely to the right, because that's what determines whether it is lesser or greater than another number of infinitely small division - like 0.(9)8, the real number immediately before 0.(9) You can also conceptualise it as 0.(9) - 0.(0)1