Numberphile video about number 11, marking the last binary day of a generation: 11.11.11. Exploring barcodes, check digits and CD technology. Filmed at the home ground of Nottingham Forest Football Club, The City Ground.

Explaining binary to understand why Pac-Man becomes unplayable after 255 levels.

We discuss the number 16 - a perfect square - and how sitting at table 16 led to something bigger for Matt Parker. In this video is Dr Ria Symonds from the University of Nottingham.

For many years, 8128 was the largest known perfect number. But what is a perfect number?

6174 is also known as Kaprekar's Constant.

69 is the largest number that most hand-held calculators can factorialize!

Why do 220 and 284 get along so well? Dr James Grime introduces us to the world of so-called amicable numbers.

Numbers can be interesting when studied in different languages and dialects - such as in Lincolnshire where we have dik, figgit and bumfit.

Tom Crawford discusses drag - then we drop the Empire State Building and Eiffel Tower into the ocean...

Eric Lander discusses how quasiperfect numbers gave him a start...

Professor Ed Copeland shows a proof by Joseph "Voldemort" Fourier that e is irrational.

This video features Tim Harford.

Featuring Tom Crawford.