Solve this equation. Then turn it upside down and solve it again. What a wonderful curiosity! The Talwalkar square (multiply by lines group theory) …

# Math

This is harder than it looks! Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Playlist to watch all videos on …

Featuring Ben Sparks discussing the Mandelbrot Set (and Julia Sets). More links & stuff in full description below ↓↓↓ More videos with Ben: …

There is now a mathematical theorem named after Sheldon. Sources Siouxland News article …

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 …

Around the world, 17-18 year old students struggled to solve this kind of question. Can you figure it out? My video on the AM-GM inequality …

Can you see the pattern? Apparently geniuses can figure out the answer right away. Source …

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: …

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 …

Fields Medallist Charlie Fefferman talks about some classic infinite series. More links & stuff in full description below ↓↓↓ Charles Fefferman at Princeton: …

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.

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 …

This is a fun basketball problem with an unexpected result! Sources http://www.math.utah.edu/~palais/mst/frequency.pdf …

Matt Parker discusses multiplicative persistence. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) Extra footage: …

Good luck with your picks! References https://www.ncaa.com/news/basketball-men/2019-02-13/absurd-odds-perfect-ncaa-tournament-bracket-put-perspective …

Just a short problem for the upcoming Pi Day! Can you figure it out? Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1 Playlist …

42 is the only remaining (eligible) number below 100 which has not been represented as the sum of three cubes… 33 was cracked by Andrew Booker from the …

This is a fun little problem, can you solve it? The problem is from Manan Shah’s website Math Misery? which has many fun problems. Check his website out: …

The internet is loving this math trick which makes many calculations much easier! Sources/references …

How many points do you need to win and avoid relegation from the English Premier League? See Brady’s Blog for more info: …

The psychologist Max Wertheimer was friends with Albert Einstein. In 1934, he wrote a letter to Einstein that contained a simple brain teaser. Can you figure it out …

Matt Parker talks about numbers – as he often does. His book “Humble Pi” is at: http://bit.ly/Humble_Pi More links & stuff in full description below ↓↓↓ The book …

A problem for 7 year olds has students and parents confused. Can you solve the problem, without using algebra? Source …

Thanks to León from Argentina for suggesting this problem! It comes from the 1995 Mathematical Olympiad, and I will explain how you could solve it in your head …

James Grime on the Hadwiger–Nelson problem. Check out Brilliant (get 20% off their premium service): https://brilliant.org/numberphile (sponsor) Extra footage …

This question stumped some of the smartest maths students in Australia, and there’s no way I would have solved it in an exam! Can you figure it out? Syndey …

Get your first audiobook free with an Audible 30-day trial. Go to http://www.audible.com/numberphile or text numberphile to 500 500. More links & stuff in full …

Oxford ranks as one of the best universities in the world. Can you solve this problem, which is adapted from an admission interview question? Source …

Featuring Simon Singh – catch him on the latest Numberphile Podcast too… https://youtu.be/kOttzKC33Vk More links & stuff in full description below ↓↓↓ Catch …

Thanks to Himanshu from India for sending me this problem! It was part of a math competition where you had about 1 minute to solve each problem (I admit I …

Zandra Vinegar demonstrates a card game and how she likes to visualise a proof associated with it (involving a hedgehog). More links & stuff in full description …

This is a fun probability riddle. A 7 sided dice has integer sides from -3 to 3, and an 11 sided dice has integer sides from -5 to 5. You pick a dice, and I get the …

In parts of the United States, the temperature in F is nearly the same as in C. When are the two temperature scales exactly equal? I go over this common textbook …

This is a pretty tricky problem. Can you solve for the angle? Watch the video for the solution. I thank Barry, and I thank Akshay Dhivare from India for suggesting …

Featuring Neil Sloane… Check out Brilliant (and get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full description …

This video features Gordon Hamilton. More links & stuff in full description below ↓↓↓ Gord’s mathpickle website: http://mathpickle.com The Dollar Game: …

A book’s barcode may look like a bunch of random digits, but there is a secret mathematical code hidden in the barcode, which you can even use to perform a …

Featuring Tony Padilla… Check out Brilliant (and get 20% off their premium service): https://brilliant.org/numberphile (sponsor) More links & stuff in full …

Can one of the characters prove she is invincible and cannot die? Let’s calculate the odds of surviving such an experiment. Source …

This popular problem is stumping everyone, and many, many people emailed it to me. I give extra thanks Chaitanya from India who was the first person who sent …

Photomath can’t solve this, and neither can Mathway, Symbolab, or Desmos. Can you? I explain how you can. A similar problem was given to high school …

This is a really fun geometry problem. It comes from the UKMT, a test which is part of forming the Olympiad team in the UK. Thanks to Liam for sending it to me!