Friends and Strangers Theorem

Alex Bellos discusses how the Incans used knots in string (Quipu) to record numbers.Check out Brilliant (get 20% off their premium service): https://brillian...

A famous mathematical theorem explained with the help of Facebook, One Direction and a collection of Numberphile's Facebook followers.

Videos features Simon Pampena - https://twitter.com/mathemaniac

NOTE: Yes we should have used greater/equals symbols at around 5:15, but the meaning pretty clear and Brady and Simon live about 10,500 miles apart --- so not worth a re-shoot!

More on the theorem: http://en.wikipedia.org/wiki/Theorem_on_friends_and_strangers