Vampire 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...

To mark Halloween we're discussing vampire numbers.

More cool sciencey Halloween videos at http://www.youtube.com/playlist?list=PL9eEsN9D48mf8CIYU1wRnWak0lcAnJN1u

This video features Dr James Grime and Professor Ed Copeland.