Math

Johnny Ball discusses Archimedes and the volume of a sphere. Check out https://www.kiwico.com/Numberphile and get 50% off your first month of any subscription (sponsor) More links & stuff in full description below ↓↓↓ Johnny Ball: https://johnnyball.co.uk More Numberphile videos with Johnny Ball: http://bit.ly/Johnny_Ball Johnny Ball books: https://amzn.to/3v8Xxqx Numberphile is supported by the Mathematical Sciences Research
0 Comments
Can you solve this interesting geometry problem? References Solution by “WAY TO GOVT JOB” on YouTube Stretched length of band https://www.thestudentroom.co.uk/showthread.php?t=1936482 Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a
0 Comments
Featuring Ben Sparks. More links & stuff in full description below ↓↓↓ Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) This is the first of a trilogy of dice tricks with Ben Sparks… More to come soon… Martin Gardner called this trick “Hummer’s Die Mystery” and attributed it to Bob Hummer in
0 Comments
Can you solve this challenging problem? Thanks to Ramesh for the suggestion! 0:00 Problem 1:18 Method 1 4:11 Method 2 (Sorry about the repost! In the previous video I had m = -1 by mistake around 3:05. I thank Andy Chen for alerting me of the typo! This is the original video: https://youtu.be/w6xul7j4t_U) Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1
0 Comments
Can you solve for the area of the square and the length of the tangent line? Special thanks this month to Fiona Harper, Kyle, Mike Robertson, Michael Anvari, Robert Zarnke. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Adapted from a puzzle by Twitter @Cshearer41 (Catriona Agg) A semicircle and quarter circle inside a square. How
0 Comments
Featuring Neil Sloane from the OEIS – and his carpenter’s plane. Mandelbrot papers offer: https://www.patreon.com/posts/52011294 More links & stuff in full description below ↓↓↓ More Neil Sloane videos: http://bit.ly/Sloane_Numberphile The OEIS: https://oeis.org Discuss this video on Brady’s subreddit: https://redd.it/nrba65 Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by
0 Comments
Students in the UK faced a similar question to this one. Can you figure it out? Adapted from [GCSE Edexcel Further Math] How would you solve for x? from HomeworkHelp Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you
0 Comments
This video features Johnny Ball. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Johnny Ball: https://johnnyball.co.uk More Numberphile videos with Johnny Ball: http://bit.ly/Johnny_Ball Johnny Ball books: https://amzn.to/3v8Xxqx Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by
0 Comments
I received many requests for this challenging problem. Can you solve it? Thanks to Toli for the suggestion! Geometry solution in method 1 http://128.192.17.191/EMT668/EMAT6680.F99/Estes/15degrees/15degreesgeometric.html Another geometry solution http://128.192.17.191/EMT668/EMAT6680.F99/Estes/15degrees/solution2.html Trigonometry solution http://128.192.17.191/EMT668/EMAT6680.F99/Estes/15degrees/15degreestrigonometric.html Go Geometry discussion https://gogeometry.blogspot.com/2009/11/problem-395-square-15-degree.html https://drive.google.com/file/d/1A0Az5nJ9wGBwcM2F4gQY2dSfeKJZ1gSS/view Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I
0 Comments
Tom Crawford discussing roulette and gambling with a famed strategy. More Tom videos on Numberphile: http://bit.ly/Crawford_Videos More links & stuff in full description below ↓↓↓ Tom Crawford’s website, with links to his work and other outreach: https://tomrocksmaths.com Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox,
0 Comments
Can you solve this tricky algebra problem? 0:00 Problem 0:49 Hints 4:12 Solution Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate I
0 Comments
Sequence guru Neil Sloane on a sequence which puzzled him – until he spotted the mistake! More links & stuff in full description below ↓↓↓ More Neil Sloane videos: http://bit.ly/Sloane_Numberphile The OEIS: https://oeis.org Hanny’s Voorwerp: https://youtu.be/RDr6bSB6Vlg Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a
0 Comments
This problem is adapted from the first round of the 2017 Dutch Maths Olympiad. Special thanks this month to: Robert Zarnke, Marq Short, Kyle, Mike Robertson, Michael Anvari. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Reddit Math Riddles Simple square puzzle from mathriddles Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many
0 Comments
Asha and Lata are two sisters with mathematically interesting ages. If you write Lata’s age after Asha’s, you get a 4 digit perfect square. Amazingly the same thing happens if you repeat the exercise in 11 years. How old are Asha and Lata currently? 0:00 Problem 1:09 Difference of squares 2:25 Solution Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send
0 Comments
Featuring Ben Sparks. Check out https://www.kiwico.com/Numberphile and get 50% off your first month of any subscription. More links & stuff in full description below ↓↓↓ Extra footage from the making of this video (including Brady trying to roll 50 points and his game against the online Pig Player): https://youtu.be/zD9-V9Idbug Ben Sparks: https://www.bensparks.co.uk More Ben Sparks
0 Comments
Thanks to Thinh for suggesting this problem! What is the area of a single square? A version of this was given to 12-13 year olds in Vietnam. I admit I didn’t see the trick, but it is a fun one! VN Express (in Vietnamese) https://vnexpress.net/bai-toan-cau-kinh-7-o-vuong-4169822.html Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end
0 Comments
Can you solve this equation? Thanks to Hrigved for the suggestion! Reference https://math.stackexchange.com/questions/438452/find-all-real-numbers-such-that-sqrtx-frac1x-sqrt1-frac1x Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate I
0 Comments
OEIS founder Neil Sloane with more sequences to ponder – of course! Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ More Neil Sloane videos: http://bit.ly/Sloane_Numberphile Visit the OEIS: https://oeis.org/ Today’s featured sequences: https://oeis.org/A008864 and https://oeis.org/A001043 Numberphile is supported by the Mathematical Sciences Research
0 Comments
Can you solve this fun little geometry puzzle? Thanks to Roman for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an Amazon Associate
0 Comments
Two boats make a round trip from opposite shores of a lake. They meet and pass at 500 units from the left shore, then at 300 units from the right shore. The boats move at a constant speed and turn around instantly from the shores. What is the distance between the shores? What is the
0 Comments
Neil Sloane from the OEIS has another number sequence which escalates quickly. More links & stuff in full description below ↓↓↓ More videos with Neil Sloane: http://bit.ly/Sloane_Numberphile Levine’s sequence on the OEIS: https://oeis.org/A011784 Neil is the founder and keeper of the The On-Line Encyclopedia of Integer Sequences: https://oeis.org/ Numberphile Podcast: https://www.numberphile.com/podcast Unmade Podcast: https://www.unmade.fm/ Numberphile
0 Comments
This is a fun algebra problem. Can you figure it out? Thanks to Aslah from India for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for
0 Comments
Can you solve this geometry problem? Thanks to Lucas from Brazil for the suggestion! Kangaroo Maths 2020 https://www.matematica.pt/en/docs/kangaroo/enunciados/2020/2020_Grade9-10.pdf Proof of inscribed angle theorem https://www.khanacademy.org/math/geometry/hs-geo-circles/hs-geo-inscribed-angles/a/inscribed-and-central-angles-proof Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I
0 Comments
Professor Mike Merrifield discusses diagrams popularized by Florence Nightingale. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Professor Mike Merrifield is an astronomer at the University of Nottingham, UK. He’s updating his own Nightingale diagram regularly on Twitter: https://twitter.com/AstroMikeMerri More videos with Mike:
0 Comments
Alex Bellos discusses how numbers were written in ancient Cuneiform. More links & stuff in full description below ↓↓↓ More from this interview on Numberphile2: https://youtu.be/n-sxOVSZc-Q Alex Bellos website: http://www.alexbellos.com And his books on Amazon (including the Language Lovers Puzzle Book which features cuneiform): https://amzn.to/3czJjXl More Alex Bellos on Numberphile: http://bit.ly/Bellos_Playlist Search the British Museum
0 Comments
Happy #PiDay! When two of the hardest tests in the world cover the same problem, you know it’s a big deal. References Wikipedia article https://en.wikipedia.org/wiki/Proof_that_22/7_exceeds_%CF%80 Putnam exam 1968 A1 https://prase.cz/kalva/putnam/putn68.html JEE Advanced 2010 Paper Solutions Part-1 | IIT-JEE | Strategy, Tips, & Tricks | Paper Discussion (see around 55:30) Proving 22/7 is greater than PI
0 Comments
Kit Yates explains how he calculated that all the SARS-CoV-2 in the world would fit inside a Coke can – and discusses “Fermi Estimates”. More links & stuff in full description below ↓↓↓ A little extra from this interview on Numberphile2: https://youtu.be/4qVM5CbKnF8 Kit Yates website: https://kityates.com More coronavirus content on Numberphile… The Coronavirus Curve with
0 Comments
Can you solve this tricky math problem? Thanks to Asad for the suggestion! Art of Problem Solving 2019 AIME Problem 3 (there are many solution methods) https://artofproblemsolving.com/wiki/index.php/2019_AIME_I_Problems/Problem_3 Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to everyone but I consider all ideas! Like many YouTubers I use popular software to
0 Comments
Can you solve this tricky question from the CSAT? Thanks to Sean from South Korea for the suggestion! Special thanks this month to: Mike Robertson, Michael Anvari, Kyle. Thanks to all supporters on Patreon! http://www.patreon.com/mindyourdecisions Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to everyone but I consider all ideas!
0 Comments
Can you solve this challenging problem from the Mathematical Olympiad of Singapore? Thanks to Truong from Vietnam for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to everyone but I consider all ideas! Like many YouTubers I use popular software to prepare my videos. You can search for
0 Comments
“You have to solve this yourself, otherwise you won’t see how beautiful it is,” Lee Sallows. SoraNews24 Sinisterly simple math puzzle for elementary school kids stumps Japanese Twitter adults IT Media (Japanese) https://nlab.itmedia.co.jp/nl/articles/1706/15/news078.html Nob’s Number Puzzle (Nobuyuki Yoshigahara (芦ヶ原 伸之)) https://dodona.ugent.be/en/exercises/1191761379/ Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to
0 Comments
Featuring Tom Crawford. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Extra footage from this interview: https://youtu.be/EsX9y0lKsZw Tom Crawford’s website, with links to his work and other outreach: https://tomrocksmaths.com More Tom Crawford videos on Numberphile: http://bit.ly/Crawford_Videos Infinity Paradoxes: https://youtu.be/dDl7g_2x74Q Vuvuzelas on Sixty Symbols
0 Comments
Can you solve this challenging Valentine’s Day problem? Thanks to Stéphane from Belgium for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address at end of many videos). I may not reply but I do consider all ideas! If you buy from the links below I may receive a commission for sales. (As an
0 Comments
This was asked to students in Indonesia. Can you figure it out? Special thanks this month to: Michael Anvari, Kyle, Mike Robertson. Thanks to all supporters on Patreon! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to everyone but I consider all ideas! Like many YouTubers I use popular software
0 Comments
What fraction of the entire circle is shaded? Jobbings, A. (2011). The Mathematical Gazette https://www.cambridge.org/core/journals/mathematical-gazette/article/9564-two-semicircles-fill-half-a-circle/6365F0D492DF2E682E71A891C782CAF6 The chalice problem Azimuth Project (John Carlos Baez) Geometry Puzzles Folding proof by Greg Egan http://math.ucr.edu/home/baez/mathematical/semicircle_puzzle_egan.gif Cut The Knot https://www.cut-the-knot.org/proofs/Semicircles.shtml Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to everyone but I consider all ideas!
0 Comments
This video features Tim Harford. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ See an extra snippet from this interview on Numberphile2: https://youtu.be/1lwocqnBmVc Tim Harford website: https://timharford.com How to Make the World Add Up: https://amzn.to/3oBcDRx Or (different title in the US): The Data
0 Comments
Can you solve this challenging algebra problem? Source https://math.stackexchange.com/questions/3844738/if-x5-1-with-x-neq-1-then-find-value-of-fracx1x2-fracx21x4 Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I consider all ideas though can’t always reply! Like many YouTubers I use popular software to prepare my videos. You can search for animation software tutorials on YouTube to learn how to make videos. Be prepared–animation
0 Comments
Archimedes’s famous Cattle Problem had a truly epic solution. Featuring Alex Bellos. More links & stuff in full description below ↓↓↓ Alex Bellos: http://www.alexbellos.com More Alex videos on Numberphile: http://bit.ly/Bellos_Playlist So You Think You’ve Got Problems by Alex Bellos Amazon: https://amzn.to/2KR9Get Signed copies via MathsGear:http://bit.ly/BellosProblemsSigned More Alex books: https://amzn.to/2KQTc5Y The Cattle Problem by AH Bell:
0 Comments
A Thanksgiving special featuring Cliff Stoll. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ More videos with Cliff: http://bit.ly/Cliff_Videos Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to
0 Comments
Professor Ed Copeland shows a proof by Joseph “Voldemort” Fourier that e is irrational. Check out episode sponsor http://KiwiCo.com/Numberphile for 50% off your first month of any subscription. The crates are great! More links & stuff in full description below ↓↓↓ Ed Copeland is a physics professor at the University of Nottingham. Check out more
0 Comments
James Maynard recently co-authored a proof of the Duffin-Schaeffer Conjecture. More links & stuff in full description below ↓↓↓ More James Maynard on Numberphile: http://bit.ly/JamesMaynard On the Duffin-Schaeffer conjecture – by Dimitris Koukoulopoulos and James Maynard – https://arxiv.org/abs/1907.04593 Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science
0 Comments
The Dynamical Uniform Boundedness Conjecture with Dr Holly Krieger. Extra from this interview: https://youtu.be/v4LWFzTyhpU Dr Krieger on the Numberphile Podcast: https://youtu.be/QmfQQzjpdpM More links & stuff in full description below ↓↓↓ More videos with Holly: http://bit.ly/HollyKrieger Holly’s website: https://www.dpmms.cam.ac.uk/~hk439/ She is the Corfield Lecturer at the University of Cambridge as well as a Fellow at Murray
0 Comments
A counterexample to Hedetniemi’s conjecture – featuring Erica Klarreich. Get 3 months of Audible for just $6.95 a month. Visit https://www.audible.com/numberphile or text “numberphile” to 500 500 More links & stuff in full description below ↓↓↓ Read Erica Klarreich’s Quanta article on this subject: https://www.quantamagazine.org/mathematician-disproves-hedetniemis-graph-theory-conjecture-20190617/ And visit her website: http://www.ericaklarreich.com/ Yaroslav Shitov’s breakthrough paper: https://arxiv.org/abs/1905.02167
0 Comments
Can you solve this delightful problem? Thanks to Elmer for the suggestion! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Send me suggestions by email (address in video). I cannot reply to everyone but I consider all ideas! Like many YouTubers I use popular software to prepare my videos. You can search for animation software tutorials on YouTube to learn how
0 Comments
Outtakes: https://youtu.be/Wrj1Kl6CHIQ Who’s Who in the video: https://www.numberphile.com/pi-million More links & stuff in full description below ↓↓↓ Patreon: http://www.patreon.com/numberphile Numberphile T-Shirts: https://teespring.com/stores/numberphile Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science. https://www.simonsfoundation.org/outreach/science-sandbox/ And
0 Comments