220 and 284 (Amicable Numbers)

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...

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

James has his own website at http://singingbanana.com/