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How To Calculate Cube Roots In Your Head

180453 ratings | 7121802 views
Here's how you do cube roots in your head! Avoid looking like Education Secretary Nicky Morgan who was stumped when asked to do a cube root: https://www.youtube.com/watch?v=x8CV0dfQMdU Note: the starting number needs to be a perfect cube. So it's more of a magic trick: ask someone to cube a number and then you can deduce their original number quickly. Check out my book "The Best Mental Math Tricks" (rated 4.7/5 stars on 4 reviews) http://amzn.to/18maAdo Can you multiply 97 by 96 in your head? Or can you figure out the day of the week when you are given a date? This book is a collection of methods that will help you solve math problems in your head and make you look like a genius. "The Best Mental Math Tricks" (rated 4.7/5 stars on 4 reviews) http://amzn.to/18maAdo H/T Mashable http://mashable.com/2014/12/12/education-minister-maths-question/ Arthur Benjamin is a Professor at Harvey Mudd College and well-known for feats of mental calculation. He explains the cube root algorithm in this pdf https://www.math.hmc.edu/~benjamin/papers/Cubing.pdf This trick is really old--here's a newspaper article from 1913 that explains the trick! http://cdnc.ucr.edu/cgi-bin/cdnc?a=d&d=SFC19130615.2.162.13.11 Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Playlist to watch all videos on MindYourDecisions https://www.youtube.com/playlist?list=UUHnj59g7jezwTy5GeL8EA_g This is the only channel to feature math topics suggested by people around the world. Support the channel on Patreon so we can share the beauty of mathematics and make the world a better place: https://www.patreon.com/mindyourdecisions If you buy from the links below I may receive a commission for sales. This has no effect on the price for you. Show your support! Get a mug, a t-shirt, and more at Teespring, the official site for Mind Your Decisions merchandise: https://teespring.com/stores/mind-your-decisions My Books "The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 4/5 stars on 34 reviews) http://amzn.to/1uQvA20 "The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 4.6/5 stars on 3 reviews) http://amzn.to/1o3FaAg "Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.4/5 stars on 13 reviews. http://amzn.to/1GhUUSH "Math Puzzles Volume 2" is a sequel book with more great problems. (rated 4.5/5 stars on 6 reviews) http://amzn.to/1NKbyCs "Math Puzzles Volume 3" is the third in the series. (rated 4/5 stars on 6 reviews) http://amzn.to/1NKbGlp "40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.4/5 stars on 13 reviews) http://amzn.to/1LOCI4U "The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.8/5 stars on 5 reviews) http://amzn.to/18maAdo "Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 4.4/5 stars on 5 reviews) http://amzn.to/XRm7M4 Connect with me My Blog: https://mindyourdecisions.com/blog/ Twitter: https://twitter.com/preshtalwalkar Facebook: https://www.facebook.com/pages/Mind-Your-Decisions/168446714965 Google+: https://plus.google.com/108336608566588374147/posts Pinterest: https://www.pinterest.com/preshtalwalkar/ Tumblr: https://preshtalwalkar.tumblr.com/ Instagram: https://instagram.com/preshtalwalkar/ Patreon: https://www.patreon.com/mindyourdecisions Newsletter (sent only for big news, like a new book release): http://eepurl.com/KvS0r
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Text Comments (5696)
ArtisticGamer1000 (2 days ago)
How about for three digit numbers?
Ishu majumder (3 days ago)
Nice
Sarvansh singh (4 days ago)
Hey what about 667376
D Matt21 (4 days ago)
Nice I will amaze my friends
its amazing (5 days ago)
Hi, at 4:12 the nearest number to 185 is 6, but you went with 5??
I don't understand Zzzs and why im watching this
alisalman hussein (6 days ago)
thank you, can you make some tutorials about mathematical modelling ??))
ABHIMAHI 47 (7 days ago)
3:30 636, closest cube is 729, so didn't we take 9 and took 8?
naveed060973 (7 days ago)
This guy is a legend He always helps me
Cara para ta feio já
javaid khan (8 days ago)
Very helpful, stay good... Find out some tricks for non perfect cubes... thanks
Harish Jay (9 days ago)
nicky morgan or nicky morgana?
Minh Hy Bui (11 days ago)
I live in Vietnam so I often mistake that comma for the decimal
Maverick Z (14 days ago)
What can we do for two digit no.s?
Michel Luedeke (15 days ago)
As an example...47*47*47 = 103.823... The nearest cube to 103 but under it is 64 = 4*4*4....the last digit is 3...the number is 43 but that’s wrong, tell if I make a mistake or does this trick don’t works every time?
Thomas md (15 days ago)
Super cool trick ☺☺😊😊
siren (16 days ago)
um okay-
Follow meback2 (16 days ago)
45,678 I am getting 32 but it not.
Pradeep sir dehradun (17 days ago)
https://youtu.be/_8kD3fxYC_E
AMAN NEYSE ! (17 days ago)
*1.000.000?? :)*
Ugly Shosho (18 days ago)
Still didn't git it 😑
Chetan Thakur (18 days ago)
If 4 digit is given ....then
prayer (19 days ago)
좋아요
Karima Rakina (19 days ago)
Its a wrong method to calculate cube root... saying we have the number : 100297 and we did the same thing as he told us to do following the same steps. We will have 43 as an answer and if we multiplied 43×43×43= 1849 that means that its not even closed to 100297 Thank you for reading this !😉
Justin Bohner (8 days ago)
43 cubed is 79507.
Karima Rakina (18 days ago)
+Tejaswi Naidu yes i think so but any way its not a perfect technique to calculate cube roots...
Tejaswi Naidu (19 days ago)
What is the cube root of 100297 ? Its 46.4617946, I think what he was referring to was about the clear calculated values only.
Bracia DPW (19 days ago)
miało być po polsku a nie po angliku to jest polski film kurwa
Doctor MicroTense (20 days ago)
I memorized squares and cubes up to 30 when I was 7
Doctor MicroTense (20 days ago)
tHis is rigged, you cant do this with many other numbers
James Monaco (20 days ago)
Prime numbers? How could this help to find the cube root of 2,3,5, 7, 11, and 13? Won't help for 4, 6, 8, 10, or 12 either.
Super trick sir Babulous
Wasim Akram Syed (21 days ago)
Is 185 close to cube of 5 or 6 ?
Aphin Shaji (21 days ago)
I hate mathematics
WonYoung Jang (21 days ago)
암산으로 세제곱근을 찾는 방법
JITENDRA KUMAR (21 days ago)
Sir video language in hindi
Scientific Creature (21 days ago)
I calculated cube root of 636 059 to 89 when it's actually 86.001...
Rodrigo NA (22 days ago)
by this method, the cube root of 27004, 27104, 27114 and several others would give 34 also, or did I wrong? I know that these numbers do not have entire roots. Translated from portuguese to english by google translator. Sorry for any mistake.
Himanshi Varshney (22 days ago)
What to do when find out the cube of number containing 1,2,or 3 digits and also with the non perfect numbers??
Selinor578 (22 days ago)
So the cubed root of, say, 636,976 is *also* 86??
Gagan Gupta (23 days ago)
4:08-- cube root of 185,193 185 is closer to 216 that is cube of 6 not to 125
HsienFx (24 days ago)
this is so sick bro!!thanks for teaching this.
Caver Gamer (25 days ago)
12 didn’t work
1004Benny (25 days ago)
I have never used a cubic root in my life, except for academic purposes... In fact, I have never used a square root either. Really, in fact, all my plants and trees have non-geometrical roots whatsowever!
Lens Apperkot (26 days ago)
37^3=50653
심승민 (26 days ago)
오역 보소 뿌리? ㅋㅋㅋㅋ
Mystery girl (26 days ago)
When term is of two digit 🤔🤔
Vedant Sinha (22 days ago)
Well if you learn the cubes of 1 to 10, you will get to know the answer itself...
xXx_MlgTr1kSh00ter _Xx (26 days ago)
Now the question is What if the Cube numbers that needed to be rooted is not perfect like some decimal difference on it
Hoimontee Das (27 days ago)
Its a very good video.... nice
김보성 (27 days ago)
It’s too hard to understand completly because it was directed in English.. So Why don’t you insert any other language in the botton of the video?? Then, many subscirber will be able to understand cube root easily! In addition, there are some errors which were incorrectly translated by Youtube’s translation system(or someone..?).
해파리 (27 days ago)
ㄹㅇ자막없어서 이해하기도힘듬 그리고 저런 잔머리로 풀시간에 newton's thorem이 훨씬빠를거같음
Spongebob NoPants (27 days ago)
Srry but i use circle roots
Thanachai Chaiyangyuen (27 days ago)
what about 7 digit numbers
Mourin moon Mahnaz (27 days ago)
😕😕
Rubies (27 days ago)
Neden bahsediyor? Hiçbir şey anlamadım.
Pancake Rilakkuma (28 days ago)
useless.... that's only integer.... not floating point cubic root....
Kuldeep Singh (28 days ago)
But 185 is closest to 6 cube also that is 216
That's a nice trick, but personally, I'd rather focus on memorizing formulas and understanding why formulas work the way they do/visualizing them geometrically. Wasting time doing cube roots when I could probably do it with a calculator faster takes brain space needed for formulas. I can't think of any educational or professional situation where this would benefit you.
kiran shahwal (28 days ago)
What is the cube of 63878
raushan jha (28 days ago)
Fuck●● this math fucks all the world's countries...Till today I was wondering only we indian are fucked by this maths....
Admiral Nutty B.B. (29 days ago)
Isnt 185 really closer to 216 rather than 125?
Shock Star (29 days ago)
This doesn’t work for all numbers, as your example at 4:00 (185,193) is in fact 57, but if you subtract one to make it 185,192 than you get 58 and since 58 > 57 the same is true for their cubes
Ayub Khan (29 days ago)
How to calculate the stage in 2 8 and 3 27
Paul Guo (29 days ago)
Doesn't work for 24677
Think Beyond (29 days ago)
See cube root of 4096 is 16 but according to you the answer is 46
SadFiere Boom (29 days ago)
Thanks i get how to do cube roots now!
Dhruv Raj (29 days ago)
What happens if it is not a perfect square? The teacher who is going to check the exam will make the answer wrong?
Mirzu42 (29 days ago)
I dont know what world you live in but 185 is closer to 216 than 125
Priyanshu Yadav (29 days ago)
Hmmm waste
DIY Tricks kashmir (30 days ago)
It is fakE
Derrick Tu (30 days ago)
He said closest to the cube without going over so shouldn’t it be 96 instead of 86 ??? Wouldn’t it be “Closest to cube without going under”?
Lavanya Bandi (30 days ago)
185 is nearer to 216 right?
Иван Ив (30 days ago)
Thanks 😊
Shade comic master (30 days ago)
Check my vid on cube roots https://youtu.be/DmSIzO0F6eU
Jarret Chan (30 days ago)
But what if it’s a 3 digit no.??
Honyoru (30 days ago)
Cube root of 39.304 is 3.4 not 34 '-'
Islam MTV (30 days ago)
whoow subtitle arabiic i will subscribe right now
Bhavesh Muliya (1 month ago)
159003 ka cube root Nikal kar ans doo
NAGHMA KAMRAN KHAN (1 month ago)
Learnt it in 7th class. Estimation method.
radhika rani (1 month ago)
What if they are not perfect cube and not more than 3 to 4 digits...?
Edison Li (1 month ago)
Calculator can do that $h!t
Nevil K Joseph (1 month ago)
What is the way to find the cube root of a number with 7 or more digits eg : cube root of 3241792
Vijay Kumar (1 month ago)
Cube root of 195206
Sneha Verma (1 month ago)
Any more examples
Rocky Handsome (22 days ago)
Hiii
Sneha Verma (1 month ago)
Smjh ni aaya
Guddu Punna (1 month ago)
I have not understand this problem
Mali Bence (1 month ago)
It's not right we need the cube which isn't closer
Mali Bence (1 month ago)
(4:30) 185 is closer to 216 than 125
farrel R (1 month ago)
*my mom taught it to me when i was 12
LifeTxt (1 month ago)
Is the cube root of 185183=57
LifeTxt (1 month ago)
Cube root of 24389 =29 and cube root of 10648=22
WeyMieYT Channel (1 month ago)
thanks its so useful!!!!!!!!
Gautham Sathiaseelan (1 month ago)
Amazing
m j (1 month ago)
큐브 뿌리를 계산하는 방법;;번역 지리네
Faizal Isal (1 month ago)
masyuk
Marino Gaming (1 month ago)
*Why is this in my recommended?*
Rony Bedo (1 month ago)
That's gorgeous 😊 Thank you so much
Sara BS (1 month ago)
Oh, I just need to memorize the table and boom 😂❤️
ABISHEKH C (1 month ago)
very useful
Abhinav Soni (1 month ago)
Not a correct method for all, find cube root of 986524 this trick gives you 104 but the answer is 99.5487669
Wish All (1 month ago)
Most useful
Icy Emerson (1 month ago)
I’ll stick to my calculator...
sean francis (1 month ago)
thats great
Sara Aamir (1 month ago)
Im jUsT a sIxtH GrADeR, l litteraly dont have a clue about what he’s saying

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