People are sharing a video about a US teacher who could not solve a problem from China’s university entrance exam, known as the gaokao. It’s a fairly challenging problem, and I show how to solve it in this video. Thanks for translating the problem into English! Tweets by ChitlangiaViral Tweets by GeraecXeupieac Tweet me Tweets

Henry Segerman (mathematician and 3D printing guru) discusses how to make three gears work together. More links & stuff in full description below ↓↓↓ Skew dice: https://youtu.be/uAnCL3vhVIs Check Henry’s book about 3D printing math: http://amzn.to/2cWhY3R Prime Numbers Playlist: http://bit.ly/primevids Prime Machine: https://youtu.be/8UqCyepX3AI You can buy the gears from Henry at Shapeways: http://bit.ly/HenryGears Support us on

People often email me that my videos helped them get a tech or finance job, which is really awesome, and I want to do more to help! So in this video I’m sharing a problem based on an interview question asked at Facebook. Source https://www.glassdoor.com/Interview/You-re-about-to-get-on-a-plane-to-Seattle-You-want-to-know-if-you-should-bring-an-umbrella-You-call-3-random-friends-of-y-QTN_519262.htm (Note: I re-uploaded this video with corrections. The original calculations

Our Pi Playlist (more videos): http://bit.ly/PiPlaylist Pi is famously calculated to trillions of digits – but Dr James Grime says 39 is probably enough. More links & stuff in full description below ↓↓↓ An extra note from Dr Grime: “Since pi39 ends in 0, you may think we could use pi38 instead – which has

This problem stumped me! But it has a pretty nice solution. Thanks to all patrons! Special thanks this month to Kyle, Michael Anvari, Richard Ohnemus, Shrihari Puranik. Source Emailed to me about 2 years ago, traced to the Australian Intermediate Olympiad given in 2013. 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 Send

T-shirt and poster details below. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Featuring Neil Sloane from the OEIS: https://oeis.org And thanks to Jonathan Wild: https://www.mcgill.ca/music/jonathan-wild OEIS A250001 – Number of arrangements of n circles in the affine plane: https://oeis.org/A250001 3-Circles T-Shirt: https://teespring.com/three-circles-numberphile

Neil Sloane discusses peaceable queens and chess. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Learn more at the OEIS entry (loads of links): https://oeis.org/A250000 References: Ainley, Stephen. Mathematical Puzzles. London: G Bell & Sons, 1977. Yukun Yao and Doron Zeilberger, Numerical and

Many students in the UK had difficulty with a similar problem on the GCSE exam. What’s the rectangle’s area, given the three circles are identical with radius r? Watch the video to learn how to solve this problem. Sources 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 Send me your favorite puzzles/suggestions by

There doesn’t seem to be enough information to solve this, but the answer works out magically. Thanks to all patrons! Special thanks this month to: Richard Ohnemus, Michael Anvari, Shrihari Puranik, Kyle. I also credit patrons Pradeep Sekar and Nestor Abad for finding a typo in my original video–thanks! Maths By Amiya : Perpendicular Chords

This is one of those puzzles that seems completely impossible to solve at first, but it has a delightful solution. Thanks to Oskar for sending me this! The problem appeared on an early round of the Norway Math Olympiad and students had about 5 minutes on average to solve the problem. The numbers a, b,

Professor Ron Graham discusses the famed Happy Ending Problem and Ramsey Theory. More links & stuff in full description below ↓↓↓ Graham’s Number (Numberphile T-Shirt): http://bit.ly/Grahams_T-Shirt An extra little bit at: http://youtu.be/hnIBiIcuudU Graham’s Number: http://youtu.be/XTeJ64KD5cg Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Numberphile is supported

3435 is Matt Parker’s “ex” favourite number – but they are still on good terms. More links & stuff in full description below ↓↓↓ Matt Parker website: http://standupmaths.com/ Filmed at the Champagne Bar at St Pancras train station in London. NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Videos by Brady

A gigantic pie is shared with 100 guests, and each guest gets an increasing percentage of the remaining pie. Who gets the largest piece? Sources https://www.theguardian.com/science/2017/jun/19/did-you-solve-it-pythagorass-best-puzzles https://puzzling.stackexchange.com/questions/52787/who-get-the-biggest-piece 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 on Patreon

Hannah Fry on parallels between the game “rock paper scissors” and lizards in nature. PART ONE: http://youtu.be/rudzYPHuewc More links & stuff in full description below ↓↓↓ EXTRA FOOTAGE: http://youtu.be/ygHwBxWyI6E Lizards by Pete McPartlan Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Subscribe: http://bit.ly/Numberphile_Sub Numberphile is supported by the

17 is the minimum number of clues required to give a unique sudoku solution – but how did mathematicians prove this? Featuring James Grime. More links & stuff in full description below ↓↓↓ Dr James Grime discusses a recent paper which cracked the problem. The paper being discussed by McGuire and others is at http://arxiv.org/abs/1201.0749

Featuring Ben Sparks discussing the Mandelbrot Set (and Julia Sets). More links & stuff in full description below ↓↓↓ More videos with Ben: http://bit.ly/Sparks_Playlist Ben Sparks website: https://www.bensparks.co.uk And on Twitter: https://twitter.com/sparksmaths Holly Krieger has done a few Mandelbrot videos on Numberphile… The Mandelbrot Set: https://youtu.be/NGMRB4O922I 63 and -7/4 are special: https://youtu.be/09JslnY7W_k Pi and the

The Big Bang Theory TV is now part of math history: there’s a theorem named after Sheldon. Sources Siouxland News article https://siouxlandnews.com/news/local/morningside-college-professors-math-appearing-in-the-big-bang-theory 73 is the best number – Big Bang Theory clip Proof of the Sheldon conjecture https://math.dartmouth.edu/~carlp/sheldon02132019.pdf 73 is the best number (other properties) 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

Thanks to Ohad from Israel for suggesting this problem! A square with side length 5 has its corner at the center of a square with side length 4. The two squares overlap, and the overlapping region has one side equal to 3 as shown in the diagram. What is the area where the two squares

Matt Parker has a new favourite number – again! More links & stuff in full description below ↓↓↓ Some notes from Matt on how far he has investigated: https://www.numberphile.com/cannon-ball-numbers Matt’s book “Humble Pi” via Maths Gear (signed and ships almost everywhere): http://bit.ly/Humble_Pi More Numberphile videos with Matt: http://bit.ly/Matt_Videos James Grime sphere packing: https://youtu.be/CROeIGfr3gs Lucas Numbers:

Have you ever heard of Mills’ Constant? Video supported by (& free book): http://www.audible.com/numberphile More links & stuff in full description below ↓↓↓ Several people have pointed out the n=4 prime is 2521008887 (we missed an 8) More on prime numbers: http://bit.ly/primevids This video features Dr James Grime – https://twitter.com/jamesgrime The Mills Proof is at:

This one stumped me! This problem is part of the AIME, a qualifying test for the US Mathematical Olympiad team. The talented students who take the AIME only average about 20 percent–it’s a hard test! Plus no calculators are allowed. Can you figure out this problem from the 1987 test? Learn the trick which results

The Great Courses Plus (free trial): http://ow.ly/C3FE30hIvhc This video features Dr James Grime. More links & stuff in full description below ↓↓↓ More James Grime on Numberphile: http://bit.ly/grimevideos James Grime: http://singingbanana.com Tackling the Minimal Superpermutation Problem: https://arxiv.org/abs/1408.5108 (Apparently I mucked up the copy/paste for the 1-6 superpermutation and, amazingly, people actually check this stuff… The

It’s not so simple to solve for this simple answer. Thanks to all patrons! Special thanks this month to: Richard Ohnemus, Michael Anvari, Shrihari Puranik, Kyle. WolframAlpha http://blog.wolframalpha.com/2013/04/26/get-real-with-wolframalpha-computing-roots/ https://www.wolframalpha.com/input/?i=cuberoot(8%2B3*sqrt(21))%2Bcuberoot(8-3*sqrt(21)) https://www.wolframalpha.com/input/?i=(8%2B3*sqrt(21))%5E(1%2F3)%2B(8-3*sqrt(21))%5E(1%2F3) 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.

This is a tricky SAT/GRE type problem that most people miss. Can you figure it out? Desmos animation https://www.desmos.com/calculator/kiswg6p0q7 Sources https://www.thisisinsider.com/hard-sat-math-questions-test-practice-2018-3 https://www.prepscholar.com/gre/blog/gre-geometry-review-practice/ 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 on Patreon to inspire mathematical discovery and