# Math

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!

A version of this problem appeared in a math competition for 16-17 year olds. Can you figure it out? Thanks to Abdelhakim in Algeria for suggesting this problem!

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

Search for Numberphile on your podcast player. See the videos on Numberphile2: http://bit.ly/Numberphile2 More links & stuff in full description below …

Fun with toothpicks. Featuring Neil Sloane. More links & stuff in full description below ↓↓↓ Neil Sloane is the founder of the On-Line Encyclopedia of Integer …

In 2007 a viral video showed the world a new and fun way to multiply numbers visually. Now I present a new discovery – a way to supercharge the visual method …

Thanks to Nikhil Patro for suggesting this problem! What is the sum of the corner angles in a regular 5-sided star? What if the star is not regular, what is the sum …

More videos with Dr Holly Krieger: http://bit.ly/HollyKrieger More links & stuff in full description below ↓↓↓ Dr Holly Krieger is based at Murray Edwards College …

This puzzle has been shared with dubious claims, but it is still a fun logic problem. Can you figure it out? Examples of puzzle and variants on social media sites …

This is good practice for math Olympiad type problems. I thank Mirza for suggesting the problem, and since I couldn’t figure it out, I also thank Mirza for sending …

Maybe pause the video and see if you can figure these out? Featuring Neil Sloane of OEIS fame… More links & stuff in full description below, including spoilers …

This comes from the “math missionary” Greg Tang whose website GregTangMath.com contains many math education games and resources. I saw it in a tweet …

Matt Parker is squaring primes. The Great Courses Plus free trial: http://ow.ly/JE3G30hIvoE (episode sponsor) More links & stuff in full description below …

This problem is baffling many people on Facebook and Twitter. Can you figure it out? I thank everyone who emailed it to me, with a special thanks to the first two …

Thanks to Matej for suggesting this problem! This is from a math competition for 14 year olds in Croatia. While the problem is challenging, “you should be able to …

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

If a ball’s velocity always equals exactly its position, how long will it take to reach x = 10, if it starts at x = 1?Thanks to Kaan and Fatih Ulupinar for suggesting this …

This challenging geometry problem appeared on one of the hardest math competitions (the Putnam exam), and there is a neat way to solve it! Thanks to all …

Featuring Neil Sloane from the Online Encyclopedia of Integer Sequences (OEIS). Lunar Arithmetic (aka Dismal Arithmetic) More links & stuff in full description …

This problem comes from an exam in 1888 for secondary school students. It was actually optional so it was considered to be a challenging problem. I bet some …

At first I thought this problem was a mistake because it seemed impossible to solve! I have discovered a truly remarkable proof of this problem which this margin …

Is there a more evil number than Belphegor’s Prime… Don’t miss the extra footage on Numberphile2: https://youtu.be/9CcI5M1LfRs More links & stuff in full …

This is a delightful problem. Find the area of the triangle defined by the four squares. It seems impossible but it can be solved with the right perspective. Can you …

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

I didn’t solve this problem myself, but I felt better when I learned WolframAlpha couldn’t solve it either! But there is a way to solve it using careful mathematical …

Did you know Google can help with math calculations? These are 5 of my favorite tricks you have to try. 6÷2(1+2) …

Here’s the video everyone requested after the average distance in a square video. What’s the average distance of two points on a circle? Can you figure it out?

Stanford is one of the top universities in the world. Can you solve these historical entrance exam problems from 1892? And thanks to Erik for finding a typo in the …

Lacking proper equipment, two friends devise a way to measure how long the train is based on their walking steps. Can you solve for the length of the train?

This is a convincing geometric argument and you have to really know your math to figure out where the mistake is. Thanks to Eszter from Hungary for suggesting …

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