Multiplying and dividing with significant figures | Decimals | Pre-Algebra | Khan Academy

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Multiplying and dividing with significant figures
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[@fransheskarivera3051]

Have been going over this in chemistry and could not understand it, explained by 3 different professors and all it took me was 9 minutes to learn. Wow. Thank you!

[@user-kf8qg8qm7d]

Why do we even need to attend school if we can just watch these 8minutes of clips regularly to learn -0- school just wastes time esp with bad teachers.. I'd do better off with myself with these videos

[@Music-bu4ff]

But school introduces children to topics the never thought of before. Wait.... video browsing does the same thing!

[@ndleinahaystack]

But what would the fat cats at the teachers union do and the overpaid wonderful teachers that make sure all children achieve academic excellence? Lol

[@koolkoala]

haruislove e you're forgetting one essential thing that you cant learn from Khan Academy, Social Skills....

[@user-kf8qg8qm7d]

kool koala I go to school, and I still don't have any social skills hehe

[@Darkmaster201107]

Iris I

[@nelsonramonortega7632]

this guy is gold

[@evan2059]

Nelson Ramon Ortega this is how this guy makes a living.

[@claudiawwjd8198]

I read “old” lol

[@Snorkyuu]

@@claudiawwjd8198 I read god

[@yneii1316]

Hey, I just wanna thank you so much. Because of quarantine and this normal, we now have online classes and I'm a very slow learner but thanks to you I learned a lot, and I was able to catch up. You teach better than my teacher. Again, thank you!!!!

[@Wolfeywolf16]

I left class kind of confused, so this video really helped. Thank you so much :)

[@mjz4865]

Kahn Academy saves the day again!

[@evan2059]

Mj Zimrin my school literally tells us to watch these to learn.

[@xxgnomexx6672]

Khan academy is the flippin G

[@MaceyRosalie]

My teacher didn't even bother teaching this material, just left us to the inevitable inaccuracy of independent learning and assigned everything over the summer -.- There's me thinking Chemistry will be the bane of my existence and significant figures are just the beginning when I stumbled upon this video :) Thank you SO much! You are keeping me from failing a torturous semester which will not even be as torturous thanks to your videos :D

[@Doomman213]

I’ve got a chemistry retake test in a few hours and this video helped me a lot, thank you man

[@gemstonepoints]

hope it went well!

[@EthanIslandGamer]

Thank you soooo much! I would have failed my Physics test if this wasn't here. It made no sense before but now it makes perfect sense. Keep up the good work!

[@abaaderaw8654]

I am a high school fresh man but Iam still to be 13 year old high school chemstry is quite hard comperd to junior but your vidos helpd me alot

[@evan2059]

It seems a lot of people don't know that this guys has his own website with courses on them. My friend did the calculus course over the summer so that he could take AP calculus his sophomore year of high school.

[@bluedaze3727]

hi evan long time no see eh

[@bluedaze3727]

es gamezone isn't dead

[@jacobstorey6395]

But what if your final answers has more than 3 significant figures before than decimal and the least amount of significant figures in the equation is 3?

[@TheLuis1094]

immensely helpful!

[@GazaAlley]

cant wait for the next video thanks man!!!

[@MakeJerold]

Anybody else here because they have a chemistry test tomorrow? Haha You are a life saver, Mr. Khanacademy!

[@adventureawaits3860]

Yep... 8years later, here I am :)

[@cxlev01]

yepppp

[@cxlev01]

dude how has life been going for ya :0

[@aliceluvsjesus]

Thank you so much! Now I got it! ^^

[@happyeverafter7788]

In the final answer, he rounded up (113.931775701 to 114), do you always have to round up?

[@khuramashfaq5067]

The best educational information 😅😅

[@hello-nq3ze]

I believe he does know how important it is for chemistry :P, he teaches that also.

[@paulceltics]

thanks; you dont know how important this is for chemistry

[@cxlev01]

this helped so much, thank you!!!!!

[@Bushnurse1]

@mathforphysics, thanks, I'll try it

[@jamesking9887]

These videos are incredible

[@rajdeeppatil3623]

Thank You from 2021!

[@danielstifanos9557]

Nothing but love!!!

[@MsEvaleon]

Thanks for the help :) !!!

[@itsukiyuuto3509]

This was really helpful

[@africanoblackaldo1569]

TYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

[@jjfjr2]

im no longer going to fail a sig fig test, thanx

[@lilychung2337]

The 1 dislike on this video is not a significant figure

[@charanm.h1767]

Lol 🤣

[@hannahhampton5667]

You're my hero. I love you

[@onefiveo1058]

get lost i hate you.

[@berdanyolcu4186]

Its perfect thanks!

[@sunlightbeautiful9677]

(134 in.)(25 in.)=3350 in. sq. When taking sig figs into consideration the solution is 3.4*10sq in sq. MY textbook says, 3.4*10cubed in sq, is it incorrect, i have been trying to figure this solution out forever now. Help!

[@dep7311]

Do not round until you are done with your calculations. If I only had watched this before college, it would have gave me a decent amount of points

[@Science_AnimoPhotography]

Hello sir i have a question Why do we even round off number when its purpose is to give an approximate number by rounding off it ? We can leave number upto the precision that we were able to measure it. Isn't this is good to do. Why even i am asking this question is because most time there is huge difference between rounded and unrounded answer upto its precision.

[@KidThatDoesEverythin]

you tripped me out when you said that there were 2 significant figures there..., i was ready to say "everything i've learned was wrong."

[@jamsheenashibu1928]

Easy understanding from u

[@CarsMisc]

THANK YOU!!!!! :D

[@shirelchandra665]

for multiplying, we wouldn't find the sig figs for 1.69 and 2.09 until after we have our answer... right?

[@vanphatphan6709]

Sal, you're a legend.

[@SpaceFlamingo07]

Finally, took way too long to find this

[@newmilm.quirante4188]

Thx man

[@bluerose543]

omg thank you soooo much. i suck at chemistry

[@arman1A94]

no we already know 114 is actually 114. so no need to put dot. Only when there are zeros after the number you put dot. That shows that you actually measured the zeros too.

[@arman1A94]

He has a degree in engineering from MIT. I am pretty sure he does

[@sozz3509]

Thank youuuu

[@vurve3406]

Thanks i was sick today and couldn’t go to school

[@snowpixie15]

My teacher sucks. I wish we had just watched this in class.

[@maxpayne5257]

Thank you big time

[@8787crosbylover]

dude i love you so much

[@chotatopips4177]

Guys, I was thinking about this and I was really confused.. If the bathroom's breadth was 10 ft rather than 10.1 feet, we'd have only 2 significant figures so the answer would be 11 tiles.(what I thought) However, according to the last video you have to include the zeroes after the decimal point too, so it would be 10.0 feet, which is 3 significant figures, for anybody who had the same questions.

[@orxana3243]

so 10.1 has 3 sig figs? thats what i thought too

[@chotatopips4177]

@@orxana3243 yep

[@AJnewt]

You would round it to the nearest 10 feet. You would probably end up with 110 tiles. 110 is still only 2 significant figures because the 0 at the end is only a placeholder. Otherwise you would write it as 110. Tiles to indicate the additional accuracy. Hope this helps!

[@NoRefundsXD]

Don't you need a decimal after 114 (like 114.) because isn't it ambiguous? Someone clarify please?

[@hedyasaid3097]

oo ma good khan acedemy best OO MA GOOD

[@talgatjarkinbayev4677]

thanks a lot

[@chrismatlopez]

Thx dood you help me

[@Liizyay]

I screwed up my last paper. hope I pass the second one :(

[@Wakaranai43]

this man is better than my physics teacher

[@MrMcbrado]

He forgot to account for grout lines and ~10% scrap. This bathroom floor is not getting done today!

[@gemstonepoints]

lol

[@sage1wt]

10.1 has 3 sig figs not 2 but thanks for the help

[@ahsanmohammed1]

Clayton Reynolds Exactly what I thought and immediately went to the comments to see if someone else noticed as well.

[@spideyman6099]

@@ahsanmohammed1 he corrected it though

[@jc-ke3ll]

you're gonna always want to round up if you are trying to determine how many tiles you need

[@mikefochtman7164]

Hehehe... You are so right. Even more than that. When laying tiles you often have to cut to fit on one side. The part left over after the cutting often cannot be used to 'fill in somewhere else', because you need a finished edge. So for example if you have 1ft square tiles and you need a strip of 2 inches along one side, well you can cut two strips from one tile (from opposite edges of the tile) but you have to throw the remaining 12 inch by 8 inch piece away. But that's a bit beyond the scope of this video. ;)

[@woo216]

excellent

[@xenomann442]

So what if I have 300/2=150 do I round to 200 because we just divided using 1 significant figure?

[@leagueof1vs178]

Do you know the answer of the problem? ((After 3years))

[@gemstonepoints]

@POP POP It's been 7 years now. I wonder if they realized it by now lol

[@Kokurorokuko]

If you're working with real-world numbers, then yes. If you work with abstract precise numbers, then no - you don't round to anything.

[@megajonathan96]

what program is this?

[@anushka17xoxo]

Man, I just hope that I don’t round off or something in my math exam🤞🏻

[@ceanpick4271]

Lol

[@Bushnurse1]

The video stops at 1:10 seconds. Just when the calculator shows up. Does this happen to anybody else?

[@alisonjay5522]

what app is he using?

[@marcopilotto6101]

What I don’t understand is that this is supposed to give you an answer that shows the worst tool you measured with so it doesn’t seem more accurate than it is. In that case, why wouldn’t you round to the smallest unit in the less accurate number. Ex: 1.745 x .009 both tools are capable of measuring up to the hundredths place but with the significant figures rule our answer can only have a ones place because of the .009.

[@annoloki]

@spirituelconnexion That is the situation though. Khan Academy has received funding from the likes of Bill Gates and Google, and this allows it to be provided to people all round the world, translated into different languages etc etc. Voluntary contributions are much easier to manage than for Khan to implement some system of establishing what each person can pay and having mandatory subscriptions based on that. The costs of running a means based mandatory payment would be silly.

[@kimchiat12]

he corrected it during the video

[@sam-mb7yi]

But you can’t have a decimal of a tile so surely you have to round down because thats the most full tiles you can have

[@timar03]

@Mugwump720 we want the math to be precise so we shouldn't round. The more Calculations you have to do the less precise will be the final answer if you round every single one of them. Rounding the numbers is not important for the Math. Its only making some calculations less troublesome with less digits and the answers will be clearer.

[@mar8014]

this was one of the hardest parts

[@Mugwump720]

I don't understand why we don't round off until the end. Can you show an example of why rounding off too early be wrong?

[@jaredglorius9084]

THE QUOTIENT!

[@evan2059]

The 20 dislikes are from people who just learned this and came here to brag about how much the know.

[@bluedaze3727]

just because you and sal are a thing doesn't mean you have to be such a white knight for him

[@dogeness]

I'm pretty sure he does ;D

[@momshadalvee]

at 8.06 u actually have THREE significant figures not TWO- Anyways really helpful :)

[@lpshalo618]

+norefundsXD ur username, and the picture together????? XDDD = BOOTIFULL.

[@raphaelseth8121]

Oooooohhhhhh 1.69....... *insert lenny face*

[@momshadalvee]

oh u corrected it- Never mind :P

[@Eln01758]

video has no sound??

[@abaaderaw8654]

Wow this vido was made when I was only 1 year old 😅😅😅😅😂😂😂

[@Max-gy5rp]

Alright but here's this: 2.124 mm × 65mm = 138.06^2 Answer in sig fig. But how? If I were to round the answer in only two sig digs (since the second number being multiplied has only 2 sig figs), I'd have to round 138.06^2 in two sig dig. Which of those numbers would I round it into two? 13? 38?

[@kayleereeder4182]

That's the problem I've been having!!!

[@Max-gy5rp]

@@kayleereeder4182 Still haven't figured it out ;n;

[@IJake15]

Basically, you'd use scientific notation. So 138.06 would be 1.3 x 10^2 in scientific notation. Also in scientific notation, the numbers to the left of the multiplication are significant. Also, why did you include squaring your answer? If you were to do that and get 19060.5636 then you'd get 1.9 x 10^4. If you need any more help let me know

[@IJake15]

or if you don't know what scientific notation is just round to 2 significant figures, so it would be 130 or 19000

[@Kokurorokuko]

140 mm^2

[@spirituelconnexion]

@mushroom574 The more rich you are the more you pay, unfair or not, is how societies work. Think of taxes governments subventions and help to poor people are all from the pockets of those whom can pay. But , when I think about it again, yeah I was wrong, I take it back. If this great work became lucrative, it may loose it greatness :D KHAN, WE LOVE YOU :D:D:D::D:D:D

[@yanhesapmustafa2588]

ok, but lets say the side of the floor is not 10.1 but 10. then the smallest sig fig becomes 2 and we cannot represent 114 tiles with 2 sig figs. can anyone help me with this?

[@howtoguro]

Might be incorrect here, but 10*10=10? Since you only have 2 sig figs to work with the answer has to be presented in that format Unless you're implying it has to be signified as 1.0*10^2

[@kalvinyuan5643]

The number 10 only has 1 sig dig b/c 0 acts as a placeholder since the decimal is not present. Therefore, the answer "100" would be written as 100 still, since 100 only has 1 sig dig. The 2 zeros behind the one act as placeholders

[@Kokurorokuko]

To add to Kalvin's answer: you don't use the rule of significant figures when working with abstract precise numbers.

[@arun2435]

Chakra of 9 tails

[@shiverain]

and physics

[@mushroom574]

@spirituelconnexion khanacademy is a non profit organisation and I think having a fee contradicts the purpose of an organisation. The fact that this is free is the reason why it is so great. Khan isnt doing this for money, hes doing it because it helps everyone. Introduce a fee, some people might lose interest, so it doesnt reach everyone. Also, do you see the unfairness in making rich people pay and poor people not? You get the same help/guidance, but only parts of the population have to pay.

[@weweweLit]

Wat if u have 3.25 *1.1+2?

[@XxAlex530xX]

iEatPusiLikeiHaveaDisease same

[@dotreaction6969]

Imagine responding 4 years agoooo

[@pavanbpatel9781]

Sir.... Wat will be the significant figure of 12*12

[@mrghosty271]

pavan patel 14

[@balkaran7081]

ambiguity

[@mrinmoyeec.kalasikam9330]

pavan patel he specified that this is only for decimals. the answer of 12 x 12 would still be 144

[@barathkumarg4214]

140

[@jonjonjon1370]

i know this is random, but since pi is infinite, shouldn't it's length be infinite?

[@jpod4237]

yes

[@myname937]

What if it's multiplied with 2 significant figures

[@shirelchandra665]

then the answer will also have 2 sig figs

[@thomasbatchelder4983]

Figurs? XD

[@paulceltics]

this was sarcastic

[@tristoncriswell3254]

WWWWRRRRRRRRYYYYYYYYYYYYYYYYYYYYYYYY *screams in DIO*

[@shirelchandra665]

dio as in the school???

[@erzas556]

what's this guy's name?

[@yahiaali6403]

im a 7 grade student and i study the significant figures plzzz help me and make a video about how to find it on the calculator

[@keerthivasanr8865]

dude how are u

[@A..R..C.]

Mans prolly chilling in his third year of college.

[@ruthtyson2110]

no 1.69 jokes lol

[@JusBidness69]

who voted this down? the kid was just asking a question...