A Math Problem That Even Geniuses Get Wrong

This simple math problem often baffles even really smart people. Can you solve it?
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[@Deathnotefan97]

My exact thoughts when adding these: 1 thousand 1 thousand 20 1 thousand 50 2 thousand 50 3 thousand 80 4 thousand 80 -5 thou- 41 hundred

[@goodyking6732]

5 thou 41 hundred? So, in numbers, 5000, 4100. You thought the answer was 9100? I don't understand what you mean, please explain.

[@holychaos453]

+Goody King See he scratched out the 5 thou? He originally was thinking 5 thousand, then realised his mistake before he finished saying it, and then arrived at the correct answer

[@Deathnotefan97]

Just remembered that -strikethrough-, *bold*, and _italics_ don't appear when viewing on mobile, they probably didn't see it But yeah, I started thinking "5 thousand" but corrected myself halfway through

[@BrutalOverride]

They appear on mobile

[@Deathnotefan97]

Brutal Override They do now, and I love the fact that they finally added that feature At the time of the comment however, mobile users had no way of seeing them

[@MrPaulc222]

Unusually, I had no problem with this, but I can see how people might be lulled into thinking 5,000.

[@machtharry]

In my mind i was like "5000, oh wait, bullshit - 4100" So yes 5000 was the first thing that came to my mind but it took me like half a second to realize its wrong. Expected much more from this video....

[@kimi20F1c]

+machtharry Same here....

[@danielyuan9862]

I still think that's a success of a video for trying to prove you can't add.

[@12jojimbo]

Very interesting question. I noticed when I was adding it up, when the "80" in 4080 ticked up to "100" my brain instantly went to increase then next digit up by one. However, it seems that my brain isn't actually paying attention to the order of the numbers I'm holding in my head. I'm not treating the "0" in the 100's digit as an actual number so my when time came to increase the next number, it skipped it and increased the 4 to a 5.

[@yatharthsikaria5931]

Correct

[@yatharthsikaria5931]

Nobody would have thought of that

[@yatharthsikaria5931]

I did that mistake only

[@skad2058]

I ended up with 3100 xD At the 1030 I added 30 and forgot to add 1000 lol

[@Sparlock42]

@@skad2058 I did both those things, but managed to catch it before the next number because I was paying closer attention than usual.

[@FiairFlair]

I got it right and I tried not to over think it or to stop it catching me out. For me, what made it simple was visualising the digets in columns, ticking over in the way old car odometers do. The third column from the left can tick over to the second column, but can't immediately influence the leftmost column.

[@ethanjames5165]

uhm why would anyone get that wrong..?!

[@mooncowtube]

+Ethan Goepper When adding these in your head, you're trying to hold the thousands in one count and the tens in another and then you need to carry the tens. Under time pressure, and trying to hold the numbers in memory, it is easy to mistake the columns and "carry" the tens into the thousands rather than the hundreds. Ironically, a lot of people watching this video probably didn't actually make that mistake who normally might, because they were primed to expect a twist or a complication and so were being extra-careful. Certainly, most people would rapidly realise their mistake once it was pointed out -- it is purely an "in the heat of the moment" effect.

[@drackonath2610]

+Ethan Goepper IKR it was sooo easy

[@lieveserpieters9163]

+Dave Clark That is the most perfect thing ever.

[@ethanjames5165]

+Dave Clark well written and good explanation. Thanks!

[@lieveserpieters9163]

I did pass it the first time i did it

[@fernandopizarrovillagarcia6992]

The brain recognizes falsely that 4080 + 20 will turn into 5000.

[@jumpingjflash]

You are the only one that actually answered the question, "Why do people get this wrong?". Everyone else is full of "I got 4100 first time".

[@missdragon5892]

ooooh

[@bukucinho]

Fernando Pizarro Villagarcía Reminds me of the meme of a person saying the year 3000 is only 82 years away

[@alex2005z]

I got this one but on my exam I made something like 1,5 is equal to 1/2

[@enriqueiii9209]

@@jumpingjflash Me too

[@Robi2009]

It's OVER 9000!

[@LTGSStrophox]

exactly

[@GaryLuKOTH]

+Robi_CK You do realize that 9000! is a lot more than a billion, right?

[@Robi2009]

+Gary Lu You do realize what "It's over 9000" meme is? I didn't mean 9000 factorial...

[@aliqadeer3010]

+Robi_CK The power level is OVER 9000! Right? Only Dragon Ball Z fans know : )

[@xxnotmuchxx]

Close.

[@felixp535]

Wtf I got 4100 too. This is far from being hard.

[@mooncowtube]

+Félix Pinchon The task is not hard, as such, but there is a simple mistake that is easy to make. Well done for not making it. Not everybody does, especially when they are already primed for the fact that there may be a twist or complication coming up.

[@noirblanque5324]

I got 4000 and im not sure how

[@youknowme2295]

@@noirblanque5324 you didn’t carry over a hundred when adding up

[@dnkbmc]

Yup, me too. I actually was surprised when the incorrect answer was supposed to be 5000... was expecting anything but that

[@katrinareads]

I almost went 5,000, but I caught myself and made it 4,100. I think it's because while working mental/oral math, we're missing that important step of when we move that 1 to the next column and see it's with a bunch of 0s. Instead, our brain jumps over the 0 column (which we've done nothing with) to the next column (which we have been working with).

[@sumduma55]

I think it might have something to do with the linguistics specifically. For instance, 140 is usually spoken 100 "and" 40. Whereas 1040 is generally spoken without the "and" as one thousand forty. Not everyone but enough of us do that we fell into the trap you mentioned. If we followed along with one thousand and up until the end, we likely treated the thousandths place as the hundredths place carrying the one to the wrong spot because of four thousand "and" eighty. The instructions start us off by saying one thousand and 20 after adding the first 20.

[@NoriMori1992]

Me: [thinking I'm being really careful] Video: "Most people get the answer 5,000." Me: "Wait, you mean that's not right? I was so careful! [thinks] OHHHHH. GODDAMMIT!"

[@Ryzer]

That's what I thought

[@MrPeep_]

I got 4,000😦

[@MrPeep_]

😦😦😦😦😦😦😦😦😦😦

[@K4i_x]

I’m ten years old but I get it right what’s the problem I just don’t get why people get wrong

[@1988ryan1]

It's not really the fact people are stupid so they get it wrong, it's more they are too lazy to remember it correctly so instead of seeing it as 4080 they see it as i have a 4 and an 8 with a few zeros so automatically increase the next actual number which is the 4.

[@chrisg3030]

Im_Ryan I think you have it. But maybe even the word "lazy" is too judgemental, perhaps some of us simply default more readily to approximations after a while. That's my excuse anyhow. It would be interesting to see how long the correct responders to this task can go on for before they start going the same way.

[@madijaegs1384]

I got it right

[@stephenjackson7797]

A definition of a "genius" mathematician never requires doing silly arithmetic in their heads.

[@alecdombkowski5849]

Exactly geniuses don’t need to do this math because it’s so basic

[@tfwthewhen]

@@alecdombkowski5849 they definitely need to do it, but we have lovely machines called calculators

[@warywolfen]

I got 4100, and I can't conceive how anyone would get 5000. Maybe you could explain how that happens.

[@wizard101guy5]

+Clyde Wary People carry the one over too far.

[@websnarf]

+Clyde Wary I think the point is that people apply the 20+80 carry incorrectly. But I didn't do that so ... I cannot say for sure.

[@Vanewolf29]

+Clyde Wary Personally I believe it has to do with how the problem is submitted. Usually the numbers flash on the screen for about 5 or 6 seconds. So when you get to the point of 4080... then the 20 comes up, initially my first thought was 5000, but I quickly had a second thought at 4100.. It just like +Paul Hsieh said.. incorrect carry.. at least under a timed environment.

[@icemage27]

+Vanewolf29 I agree completely. I cheated a bit by pausing the video when a new number flashed up, and I caught myself carrying incorrectly at first as well.

[@SeeMyDolphin]

+Clyde Wary I tried to do it without pausing the video. Instead of thinking of a single number (i.e. 2050) my brain just separated it into two numbers (i.e. 2 and 5) and gave them different place values. Once the ten place reached ten my mind quickly increased the next place value in my head, but since it ignored the zeroes the next place value I had stored in my head was 4. My brain increased the 4 to a 5, knew it was in the thousand place, and knew every other place value was 0, so I arrived at the answer 5000. I think there are two conditions that make this occur. First of all it's time based. You need to do it quickly, so your brain ignores details it deems insignificant (i.e. the zeroes) and stores them away in a less active area. Secondly, the operations are switching between addition in the ten place and and the thousand place. Since you are doing this quickly, when you have to carry over the one, instead of switching from the ten place to the hundred place that your brain has stored away, it switches to the thousand place which is in an active part of your brain, and has been the object that you have been quickly switching to from the ten's place since the start of the series of addition. Especially with the addition of 1030 where you basically have to do both places simultaneously. I'm not a neurologist or anything, but this is what makes sense to me.

[@jsoren9130]

I'll admit I messed up. I think it's because I was focusing so much on the thousands and tens digits changing, while the hundreds remained zero, that I automatically blanked out the hundreds and treated the thousands like the hundreds digit. With me it wasn't laziness as much as it was time pressure that added to the before mentioned factor. I haven't learned to handle pressure very well, and I tend to put pressure on myself when it comes to tests with time constraints. It tends to cause little short circuits in my brain on even simple things. Sometimes I can think quick, sometimes I can't. Definitely not a competitor in mental sprints, though. I do better at "long distance".

[@gblargg]

I was rushing too because the setup sounded like I couldn't pause, and that perhaps a whole second page of numbers would be about to show that I'd have to add quickly.

[@PattyManatty]

This isn't a math problem, but a psychology problem.

[@NoriMori1992]

+PattyManatty Everything that humans do is a psychology problem on some level.

[@chaopeteryang1272]

I see. First time I got 4100, since I used the visual method of doing addition. However, I then add it while saying it out loud, which I then got 5000. It seems like that using a verbal approach is less accurate than a standard visual method.

[@user-ry4ip9ps9x]

I didn't have any problem with this, but that was most likely because I was expecting some sort of trick and was therefore more cautious in my thinking process.

[@rafaelmeseguer382]

my mom once asked me this when i was a child, and i got it right. but recently she asked me again and i got it wrong

[@riddhimanbanerjee6556]

It's evolving... Just backwards. I hope you get it right now, it has been 5 years...

[@Allangulon]

It's an over confidence issuen

[@bone0944]

This is very simple. Your vids are normally very good, this one is well below your normal high standard. The sum is straight forward and offers no challenge to those who are only moderately capable at arithmetic.

[@Jared-vq8qg]

I GOT IT RIGHT, I quickly second guessed myself. Since 80+20 does leave a remainder, you automatically think of putting it in the thousands place that constantly changed

[@badlydrawnturtle8484]

“Why do we get the wrong answer for such a simple math problem?” Because you aren't good at mental math. I got 4,100, and had time to wonder what was supposed to be so hard before it showed the answer. I think people tend to rush too much when they do math. They put too much trust in their natural ability to hold numbers in their head, instead of double-checking as they go. Throughout my school years, I was the last one to finish a math test… and the one with the highest grade. Yes, even in timed things like this video, there is still room to take your time and double-check your result.

[@aliqadeer3010]

+Badly Drawn Turtle You are right, but the way the video showed the problem was not right. When the numbers are put down in a line, it is easy to calculate, as you can see the 100's line. The video shouldve showed individual numbers, then most people wouldve misinterpreted it. Nice Turtle though ; )

[@goodyking6732]

I think the mental tendency is to carry the one to the highest degree, especially when hundreds were previously inactive. I'm sure most who got this correct made a conscious effort to recognise the tens carried to a single hundred instead of the thousand is an instinctive assumption.

[@rogerlundstrom6926]

I didn't get it wrong.. and I would say most of my friends would not either.... Either way; I Am fairly sure that the reason people might get it wrong is because of how language works when it deal with mathematical representation, and the fact that the numbers come fairly quick...When we WRITE numbers we always type out ALL numbers, but when we SPEAK we have a short-hand where 0 values are left out.. so when the brain suddenly has to flip over to a new 100, it don't think of the 100s because up until then the hundreds had been ignored.

[@brucesekulic5443]

In conventional parlance the ‘no-hundreds’ is implicit rather than explicitly stated part way through the sum...flout convention and express the ‘zero hundred’ as you go through the summation process and then it is blatantly easier to sum correctly, when there is a hundred to carry into that hundreds column.

[@AzureKyle]

I got it right, but for a split second, I thought 5,000, then realized it was wrong and got 4,100. I believe it's because we're dealing with the thousands column and the ten's column exclusively in most of the equations, so when we get to 3,080 + 20, we ignore the hundreds column and go straight for the thousands, getting 5,000 instead of 4,100.

[@mr.upcycle9589]

The last set of numbers is were people get off. It is 4080 then you add 20. For some reason many minds lose the hundreds place value. Then 5000 comes into play. That's were it got off in my mind for just a second before I corrected myself. It is the tendency of the human mind to expect more of what has already been, you see multiple 1000's and expect more of them. We are creatures of habit and jumping to conclusions has been what has kept us alive for generations. It is the, better safe than sorry, part of our brain kicking in.

[@ameliavasconcelos9914]

i guess a 7th grade student can be smarter than a genius because I got that correct

[@MrTnbopp123]

amelia costa Me too, I dont get what he got 5000 from. But that makes for a very easy "solution" to the "puzzle", the answer why ppl get it wrong is: They dont..

[@metzgerdewsky]

amelia costa smarter? how does answering one question correctly that someone else didn't answer correctly make you smarter than them?

[@SuperHeroJay]

Erik Holtrop People got it wrong since when they added the added the 80 and the 20 subconsciously they added a thousand instead of a hundred.

[@metzgerdewsky]

Jason Truong I know.

[@fritzape]

+amelia costa Lol I guess a 5th grade student can get that right too XD

[@lovenottheworld5723]

The human mind isn't capable of knowing right from wrong. What you see you don't see, what you hear you don't hear, what you know you don't know.

[@AltumNovo]

5000 did cross my mind for second then i realised its 4100, all in the time you explained it without pausing the video.

[@SkyCharger001]

the cause is simple: when doing it fast you can loose track of the relative number positions. Padding-zeros can (but not necessarily will) reduce this problem.

[@LYLEWOLD]

Yeah, i got 5k, too. 3rd time through I saw my mistake. Wow. How easily the brain leaps to the wrong answer, with utmost confidence.

[@kurzackd]

the problem is that you warned us beforehand that it's tricky, so we were extra careful and that's how we got it right.

[@rhr5143]

The question was to add up the numbers as they appear on the screen. First numbers that add up to 4100 appeared. Then the number 5000 appeared. Then 4100. Adding up all the numbers that appeared on the screen we get 13200.

[@robertwagner9014]

Even though this is super old I thought I'd comment that the reason I had to catch myself from jumping to 5000 is linguistic: When we say numbers that from n000-n100 we do skip the 100's column. So when it was time to carry the tens column my mind did a math operation on the spoken word "4 thousand eighty" and math operations on words do not work so well.

[@Double-Negative]

i got 3100... oops

[@nikitakucherov5028]

Im here 7 years later and find it interesting that no one in 7 years got the correct answer, if you purley listen to the question without making any assumptions the actual correct answer is 13,200

[@kennethw6962]

The problem is not adding the numbers, but the way the numbers are presented. If the entire list were simply displayed on the screen, nobody would get 5000. But because they are displayed one at a time and in the particular order they are displayed (a few big numbers and then a really tiny number at the end), it throws the brain off.

[@uchiha7160]

The reason is because when we are adding two digit we are thinking 80 +20= 1000 but it is 100

[@enriqueiii9209]

True, But your adding tens not hundreds.

[@lawrencejelsma8118]

I didn't get why 5,000 some people get. Putting a bar underneath and balancing a checkbook the hand written non calculator way means adding up the columns and doing carryover so all 0s in the last column is 0 with 0 carryover in 0+2+3+3+2 in the second to the last column was 0 with carryover 1 adding again in third to the last column of 0s 1 + 0 + etc 0s = 1. Then the fourth from the last or leading column to continue (if needed) 4 1s of 0 carryover from the third to the last column (second left to right column) is 0+4. Giving 4100 or 4,100 to add in a "," break in 1000s.

[@davelordy]

I got 200, but I really wasn't paying attention.

[@СемёнКольцов-о1ы]

Yeeees! Finally I solved something from your channel. I got 4100.

[@rcb7867]

This trick pushes a lot of brain buttons. People don't get every math problem correct in one go. Double checking is always necessary. But the constraints of this -- add as you go -- make that check difficult. It also applies time pressure. It taxes the short term memory. Also, it rather sneakily avoids values in the hundreds place until one is filled by the carry operation in that last step. We say to ourselves: carry the one to the next place over. But the way the work is staged, that place 'feels' like thousands. Add that to the time pressure, the multitasking of a running total, and the absence of a double check -- this situation is prime for a mistake. I'd like to see the experiment run with the first value being 130. I propose the effect vanishes: People arrive at 4200 with no problem once they're paying attention to the 100s place.

[@dawnscript1]

I got to 3100 and almost forgot to add the last 1000 so I had to look back for a second and got to 4100. I didn't have any problem that confuses numbers like others may have, and this is probably due to me recently practising 6 digit addition often, which means I have developed the skill of making sure the answer for each part of the question is right before moving on. This aside, I can see how the brain can trick you into thinking that it is 5000. Just like we might thin 33 + 77 = 100

[@onniruusunen9444]

I did get 4100 and did not even think about 5000. I don't know why you would get that

[@ziggystardog]

I got it right. I have aphantasia, and I add numbers in my head aurally. I treat numbers like this as 40-80, so when you add the last 20, you get 40-100 or 4100. Easy! The only way I think I might screw this up is adding mentally in other languages that use different schemes for speaking numbers.

[@dennisviviani4904]

No, He said "1050" when it was suppose to be 1030. I heard it the first time. Anyone else catch that?

[@enriqueiii9209]

+20 +30 Yes, he was adding 1000, 10020, 10050 now you try, listen to it couple times. I can't put the +20 above 1020 and +30 above 1050.

[@jellyyz6335]

Ohhhh I get it You first add the numbers 20 + 30 =50 and 20 + 30 = 50 and then 50 + 50 is 100 But you have to take away the 30 from 1030 so 100 + 30 is 130! Then add up the 1000's There's 4 of them so 1000 + 1000 + 1000 + 1000 = 4000 So then it's 4000 + 100 = 4100 What about the 30?? Oh wait I added that

[@enriqueiii9209]

There is no 130, only 1030

[@justynpryce]

My potential answer to the puzzle is to do with human psychology and learned notation when it comes to (decimal) arithmetic. When adding we see a pattern, the pattern being that when we finish off a sum like this: 9 + 1 = 10 or 180 + 20 = 200 , we see that all digits behind the first one become 0 and the first digit increases by one. So, in the case of this problem the situation we are faced with is 4,080 + 20 , Which should equal 4,100 , however, following the "pattern" we presume that the back digits all become 0 and the first digit increases by 1. This leads to the incorrect result of 4,080 + 20 = 5,000. Most people who made a mistake realized their mistake quickly after making it. Showing that this effect is probably a predicted result based on the "rules of decimal arithmetic," that we create subconsciously. It works well enough to get us through the day, but maybe we ought to just stick to a calculator when things get lengthy. Of course this doesn't explain all of it, I feel a significant part has to deal with the 0 between the 4 and the 8 meaning the hundreds place gets completely forgotten.

[@louisd95714]

I think most people get this wrong because it feels natural to go from 4,080 to 5,000 when calculating mentally.

[@hape1264]

unfortunately the pop up ads got in the way and I could not see the numbers.

[@unclemunch]

People will say how easy it is, but when adding in your head, it is easy to add 4080 and 20 and get 5000. Finding out why would be interesting.

[@sircobalt5099]

I got 4100. My brain stumbled a bit when I added 20 so it gave me a few precious seconds to realize it was 4100.

[@THall-vi8cp]

I didn't get 5,000. I got 4,080. I think the answer to the puzzle is: When people add as they go rather than seeing the final set of numbers before adding, they have to remember the past calculation while simultaneously carrying out new calculations. This is confusing.

[@l.ekkashdev]

I got 4100 and I am a genius too , so what's the problem with other people is that they take all the 20s and 30s and get a sum == 20+30+30+20= 100 and they add with remaining 4 × 1000s to get 5000 , but dudes actually you got 20+30+30+20 as 100 but your optical illusions took it as 1000 leading to the wrong estimation.

[@negative3144]

We are only adding incorrectly at the last twenty, I think if one did it on paper and writing the numbers down as they said them out loud they would get it right, but because of they way we say larger numbers, our brains may be skipping details. At the very end of adding it up we have 4080, because there is a clear zero between the 4 and 8, one can easily see that adding 20 would get 4100. However the english way of saying 4080 does not include a zero, and our brains might just overlook that there is a zero there and just skip to one thousand.

[@guessundheit6494]

They get it wrong because they're thinking in words. Add hundreds/thousands and tens/units (e.g. ten hundred, ten-twenty, ten-thirty, etc.) and you don't make the mistake.

[@nedmerrill5705]

People get addicted to adding digits wherever they find them, but get careless about keeping their columns straight using placeholders. Apparently.

[@hillaryclinton2415]

I kept getting it right, and had to slow down to see what I did.. I went 1k, 1k20,1k50,2k50,3k50,3k80,4k80,4k100... Establishing the thousands colum first, then the rest.. for each line.

[@TheVincent0268]

There are 3 white refrigerators. What is the color of the 1st refrigerator? Answer: White. And the 2nd? Answer: White. And the 3rd? Answer: White. And what does a cow drink?

[@Ttavoc]

I am a technician and therefor be very careful with numbers. I got it right but only cause every technician worth its salt was lulled in a terrible mistake by a comparable situation

[@CrystalClearMaths]

This particular adding puzzle is usually given verbally. This means that people cannot see the numbers listed. When presented in this way, the number of people who respond with '5,000' is massively increased. I have done this publicly with dramatic results. It appears that our brains recognise that adding the last figure is 'rounding off' or 'completing' a total and rounds the answer to 5,000. When people can see the figures and use (or refer to) a familiar algorithm to add them up, they are more likely to respond with 4,100. I have used this example to talk about the importance of proofs and (proven) algorithms in mathematics rather than trusting what seems 'reasonable.'

[@davidbrinnen]

Remember finding this puzzle in a Christmas cracker as a kid and trying it out on the adults and being surprised how effective it was.

[@herpsenderpsen]

wow, that's quite shocking.

[@SSNewberry]

I got 4100. The question I have is "who gets the wrong answer?" followed by "What are they smoking?"

[@nidhiagrawal3354]

At the second last you are at 4,080 but your mind thinks 4,800 and when you add 20 your mind thinks 200 and so 4,800 + 200 is equal to 5,000

[@enriqueiii9209]

True, good example

[@aum1040]

As a guy who got it right, I feel that the guy who got it wrong AND MADE A VIDEO ABOUT IT should have at least explained why he got it wrong.

[@nikolagujanicic7828]

Is someone kidding me? This is basic of basic math. I can't even see the problem here. Your concept of genius is so funny.

[@atoz4399]

I got the right answer. So I do not see why anyone would get this wrong. I was waiting for multiply, divide, subtract or anything that might get me confused for a minute. Too easy.

[@asbood112]

Simple solution to avoid that problem. Take each column on its own merits. What I did was a table (of sorts) and inputted each number in the column like a tally chart. I had a 4 in the thousands column and 2 completed tallies in the tens column which means that I should get rid of those tallies and put 1 in the hundreds column. Also as to why people get it wrong, ask a psychologist.

[@aliqadeer3010]

+MindYourDecisions Most people here probably got the answer right because you placed the numbers below eachother. It enabled them to differentiate between 'hundreds' and 'thousands'. However, if the numbers were shown individually, almost everyone would gotten it wrong!

[@zacharyferraro19]

It’s annoying cause when you click a vid the comments are visible on screen so it ruined the test for me

[@kimi20F1c]

I got it right. When the last number appeared, I was thinkin 5000 aswell, but realized my mistake later, and before he give the solve.

[@TheDigiWorld]

For about half a second I was also gonna say 5000 but immediately corrected myself to 4100

[@justsomeguywithhair6897]

'People get 5000 and 4100' Me who got 4050: Aight I'm Outta here.

[@DownDance]

I'm hurt. Deeply hurt

[@ducatius5940]

People who are wondering how it happens!!.. As it goes like a flow most of the people doesn't even concentrate on the problem as they feel it as simple.. so they think 4080 as 4980, to be clearer they just hallucinate 4080+20=5000 it's 'cuz of the previous flow with the problem.

[@LukeDavisAuthor]

As a genius I didn't get this wrong, but it is likely some genius's would. You carry a lot of shortcuts in your head and some problems like this are a hole your shortcuts fall through. I could answer 100 maths problems extremely fast and get near all of them right. Pick a 100 problems my mental shortcuts don't work for and I would get 0. I would answer very quickly lol, but still ultimately get 0.

[@gblargg]

All the numbers only had non-zero digits in the tens and thousands places, so my mind just ignored the ones and hundreds. So when it came time to carry it stuck in the earlier thinking rut. It would be interesting if variations of this had been given (not to the same person, who would perform better on second try). I predict that if the earlier numbers had generated a carry out of the thousands, the error at the end might not have been made.

[@Martykun36]

I saw that we were adding tens and there were thousands too and I went "oh better be careful not to carry the one two places" because this is a common mistake that's screwed me over so many times over the years.

[@milliehanson1970]

the answer to your question on the video is mainly because theyve been given loads of 1000 so when they add up 20,30,30,20 they think it is 1000 instead of 100

[@aliza7195]

Me who got 3110: We're not gonna talk about this (except in the comments ofcourse)

[@IS-py3dk]

Presh sir I think its because of the positions If you add the first three, you ll get 1050 Then add 1030 and 20 which is at last You will get 3000 And then 2 more thousands are remaining So 3000 + 2000 = 5000 But in reality you are getting 5000 Because :-- at last when you get 4080 You are doing it quickly and carrying over the 1 in the thousands column but infact you hafta carry it to the hundreds column 😉☺✔✔

[@JohannaMueller57]

if you're wondering WHY you got this wrong immediately after you compared solutions, you're definitely not a genius.

[@Lordmewtwo151]

"Why do we get the wrong answer for such a simple problem?" I must confess, I too instinctively answered 5000. I can't speak for everyone else, but I think that, especially adding the numbers rapidly, by the time the final 20 pops up, we are so used to adding thousands that it happens automatically.

[@xandrapauco1998]

Here's why: Me: 1000 + 20 + 30 + 1000 + 1030 + 1000 + 20 = 4100 Most people: 1000 + 200 + 300 + 1000 + 1300 + 1000 + 200 = 5000

[@johnboe1670]

should have been reading "10-00", "10-20", "20-20"... all the way to "40-100, *carry*, 41-00" then you wont accidentally add an order of magnitude

[@arundhatide3809]

+ clyde wary it is because people think that the 80 is 800 and skip from tens place to thousands place

[@beaksofeagles]

When it got to the third line, I thought "This is going to try to trick me into leaving out the hundreds column"....so I was ready for it.

[@gabrielesallemi787]

To not fall for the trick, at the end you have to thing about hundreds and not thousands

[@Lycoriste]

I was surprised I got it correct, which rarely happens.

[@baconprisons]

i had all the numbers went away for a snack and still remembered the anwser

[@terminat1]

I just passed Calculus II. If I failed this challenge, I'd be embarrassed.

[@raynebc]

I caught myself trying to add it up wrong, but corrected myself in time to beat the answer being displayed. Not particularly difficult.

[@easy_s3351]

I think you should revise your definition of a "genius". I have no idea how someone would get to 5000 unless they think 4080+20=5000 and if you think that you're more likely to be the exact opposite of a genius.

[@peterdavies1679]

I don't understand how did people get 5000?

[@estherpeng3308]

Apparently the brain falsely thinks that 4080+20 is 5000. I fell for that too.

[@markvanpopering4598]

I think it's a carrying issue. The hundreds column had nothing going on until the last step. When the tens finally had spillover, some people carried the one to the thousand thousand column, which they had been modifying, instead of the hundreds, which was unmodified before that. It didn't get me, but I could see how it was easy to be fooled.

[@colonelfredpuntridge8799]

I got it right the first viewing, and the reason I did is: I am an opera freak and amateur opera singer and a bass. So I know Leporello's "Catalogue Aria" from DON GIOVANNI, in which he describes the Don's track record of seducing women. ("Leporello" is Don Giovanni's servant, and he takes all kinds of abuse from his psychopathic master.) It includes a list of how many women he seduced in each of several countries. "In Italia seicento e quaranta, in Almagna duecento e trentuna, cento in Francia, in Turchia novantuna, ma in Ispagna son già mille e tre!" "In Italy, 640, In Germany, 231, 100 in France, 91 in Turkey But here in Spain, already 1,003!" You can't sing this without learning how to add in your head and not make careless or sleepy mistakes. (The total is 2,065. It's funny, because during the opera, he actually manages to seduce and boff ... _zero_ women, although he tries like hell.)

[@KyronAlison]

I got it because all the tens numbers add up to 100 and the thousands in the list add up to 4000 and 4000+100=4100

[@MiguelSucksAtUrbanism]

how TF did I get 4K?