Math

How many triangles are too many? Featuring Henry Segerman from Oklahoma State University. More links & stuff in full description below ↓↓↓ Check Henry’s book about 3D printing math: http://amzn.to/2cWhY3R More Henry videos: http://bit.ly/Segerman_Videos Henry’s hinged doilies were joint work with Geoffrey Irving (https://naml.us) Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook:

There’s a short warm-up puzzle followed by the main puzzle. Thanks to Greg in Hungary (warm-up) and Jorn in Holland for suggesting these problems! *In my original video, I solved for day 3 with AND but mistakenly wrote “OR”. Interestingly the OR is much easier to solve, and the answer works out to the same

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:

Mr. White, Mr. Blue, Mr. Brown and Mr. Pink are wearing shirts that match their names, but no one is wearing the same color shirt as their name. They exchange a few words that give hints about what color shirt each person is wearing. Can you figure it out? My blog post for this video:

James Grime is back and talking prime numbers. Check out Brilliant.org by using the link: https://brilliant.org/numberphile (20% off premium subscription) More on prime numbers: http://bit.ly/primevids James Grime: http://singingbanana.com Editing by Pete McPartlan Music by Alan Stewart Read about Sierpinski Numbers: https://en.wikipedia.org/wiki/Sierpinski_number PrimeGrid: http://www.primegrid.com Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We

Thanks to Alessio from Italy for creating this problem and sending it to me! A cyclist and a series of motorcycles are racing to the top of a long climb, and the cyclist doubles back. Given how many motorcycles passed the cyclist, can you figure out the motorcycles’ speed? (precise wording in video, too long

Tadashi Tokieda is talking about Borromean links again – this time using ribbons. More links & stuff in full description below ↓↓↓ More Tadashi videos: http://bit.ly/tadashi_vids Knots: http://bit.ly/Knot-a-Phile Video by Brady Haran and Pete McPartlan (animations by Pete) Music by Alan Stewart Support us on Patreon: http://www.patreon.com/numberphile NUMBERPHILE Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile

Tadashi discusses pressure and lift… with a toy of course! More links & stuff in full description below ↓↓↓ Lift and wings on Sixty Symbols: https://youtu.be/PF22LM8AbII Tadashi Playlist: http://bit.ly/tadashi_vids You can buy version of this toy on Amazon: https://amzn.to/2MLfpSC (affiliate link) Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile We are also

Thank you for 100 million views! To celebrate, here’s a puzzle related to 100 million, sent by Karin. Find a sequence of 100 million consecutive non-prime numbers. That is, every number is composite—not a single number is a prime number. The method can actually be generalized for arbitrary lengths too! Watch the video for the

A quick little problem from Cliff Stoll, who baked a birthday cake for Brady… More links & stuff in full description below ↓↓↓ A trilogy of mathematical cake cutting videos… http://bit.ly/CakeCuttingTrilogy See more Cliff videos: http://bit.ly/Cliff_Videos The scientific way to cut a cake… https://youtu.be/wBU9N35ZHIw Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): http://bit.ly/MSRINumberphile

Lattice multiplication is a fast and easy way to multiply numbers and even polynomials. You write the digits of one number as different columns and the digits of the other number as different rows. Then you multiply the digits in the columns and the rows, one by one, and add up the numbers diagonally. The

What’s the area bound by the lines x + y = 5, x + 2y = 6 and the y-axis? I present one way to solve this problem. #shorts 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 purchase

Here’s a fun game you can play with another person. The game starts on January 1. Each of two players takes turns calling out another date. The new date has to be a later date in the year with either the same month OR the same day (from January 1, a player can call out

Here are more pics of the doodle: http://bit.ly/Doodle_Images More links & stuff in full description below ↓↓↓ And make sure you subscribe to Objectivity: https://www.youtube.com/c/objectivityvideos Thanks to Keith Moore at the Royal Society – https://royalsociety.org 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

Every year some NBA team seems to make the playoffs with a losing or barely even record. This video considers how extreme the example can go. WATCH how an NFL team with 0 wins could make the playoffs: https://www.youtube.com/watch?v=3xXyauro_kc Worst nba playoff teams: http://www.sbnation.com/nba/2014/4/4/5581984/nba-playoffs-history-bulls-spurs-knicks-cavaliers NBA scheduling: http://www.nbastuffer.com/component/option,com_glossary/Itemid,0/catid,44/func,view/term,How%20the%20NBA%20Schedule%20is%20Made/ If you like my videos, you can support

Truncatable Primes with Dr James Grime… Check out Brilliant (and get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ Dr James Grime is available for public talks. See his website: http://singingbanana.com More videos with Dr Grime: http://bit.ly/grimevideos The Eastaway Prime Pencil (Pack of 11 via Mathsgear): http://bit.ly/357686312646216567629137pencil

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

More Cliff Stoll videos: http://bit.ly/Cliff_Videos More links & stuff in full description below ↓↓↓ Our first Borromean Ring Video: https://youtu.be/x6Ml4AEt0kk Tadashi does Borromean Rings: https://youtu.be/Ra9I_-o2LHM Knot playlist: http://bit.ly/Knot-a-Phile 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

Part One: https://youtu.be/wGkvyN6s9cY Featuring Tadashi Tokieda. More links & stuff in full description below ↓↓↓ More Tadashi videos: http://bit.ly/tadashi_vids Raw paperclips slow motions: https://youtu.be/zuX5yy_93JA Video by Brady Haran and Pete McPartlan (animations by Pete) 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

If the first square has a side length equal to 1, what is the sum of all blue areas? Can you solve this fascinating problem? 0:00 Problem 1:11 Hint 3:58 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

First watch how to calculate cube roots: https://www.youtube.com/watch?v=Ds8ijPsg26g If you like my videos, you can support me at Patreon: http://www.patreon.com/mindyourdecisions Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you. My Blog: http://mindyourdecisions.com/blog/ Twitter: http://twitter.com/preshtalwalkar

Featuring Neil Sloane from the OEIS. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor)… More links & stuff in full description below ↓↓↓ Part 2: https://youtu.be/HFeKdMf01rQ Neil Sloane is the founder of the The On-Line Encyclopedia of Integer Sequences. Visit it here: https://oeis.org More Neil Sloane on Numberphile: http://bit.ly/Sloane_Numberphile Numberphile is supported

Do political beliefs affect mathematical ability!? More links & stuff in full description below ↓↓↓ Featuring Dr James Grime. Here is the paper referred to: http://bit.ly/wrecksmath Maths vs Math: http://bit.ly/MathorMaths Brown papers: http://bit.ly/brownpapers 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 Haran Patreon: http://www.patreon.com/numberphile Brady’s videos subreddit: http://www.reddit.com/r/BradyHaran/

A dog, cat, and mouse run around a triangle at different speeds. Can you figure out angle ABC? It seems impossible but the answer works out magically! Thanks to Zaki for suggesting this problem. 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! Why are some

Make the equation correct by adding one blue dot, or erasing one blue dot. A single dot changes everything! Keep It 💯 Puzzle: 4 dots to make this true! Sources One of these pixels on the scoreboard should be either turned off or turned on. byu/EebamXela inmathpuzzles https://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_medium;action=display;num=1091299465 https://www.utest.com/forums/11636/page/1 Playlist to watch all videos on

Tech companies like Google have asked this question during interviews. A cat is hiding in one of five boxes that are lined up in a row. The boxes are numbered 1 to 5. Each night the cat hides in an adjacent box, exactly one number away. Each morning you can open a single box to

Some of your favourite maths jokes are dissected in forensic fashion. More links & stuff in full description below ↓↓↓ It is YouTube Comedy Week: http://yt.be/comedyweek Animation by Pete McPartlan – http://www.petemcpartlan.co.uk Explanations by Matt Parker – http://www.standupmaths.com More jokes explained at: http://youtu.be/Fmb3TCvlET Leave more joke suggestions in the comment section. NUMBERPHILE Website: http://www.numberphile.com/ Numberphile

Ben Sparks shows us a simple problem that takes some fascinating twists. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description below ↓↓↓ More videos with Ben Sparks: http://bit.ly/Sparks_Playlist Catch a more in-depth interview with Ben on our Numberphile Podcast: https://youtu.be/-tGni9ObJWk Ben’s website: https://www.bensparks.co.uk Numberphile is

What is the radius of the circle, in simplest terms involving a, b, and c? I read that even the great mind Richard Feynman made a mistake. Watch the video to learn the common mistake and what the correct answer is. Source Feynman story http://web.media.mit.edu/~walter/MAS-A12/week11.html My blog post for this video https://wp.me/p6aMk-84E Playlist to watch

Thanks Squarespace: https://www.squarespace.com/numberphile More links & stuff in full description below ↓↓↓ Full length colouring video: https://youtu.be/a-6oOVdU7Oo Alex Bellos books (including colouring books): http://bit.ly/BellosBooks Colouring by Tiffany Arment: https://twitter.com/tiffanyarment (or coloring as it is America!) Thanks to Loretta Kolakoski for pictures of William (Bill). OEIS entry: https://oeis.org/A000002 Oldenburger paper (1939) pre-dating Kolakoski: http://www.ams.org/journals/tran/1939-046-00/S0002-9947-1939-0000352-9/S0002-9947-1939-0000352-9.pdf (the sequence