5 Platonic Solids

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 are there just five platonic solids (and what are platonic solids!?)

The solids are the tetrahedron, hexahedron (cube), octahedron, icosahedron and dodecahedron.

Featuring Katie Steckles and James Grime - https://twitter.com/stecks and https://twitter.com/jamesgrime

Our thanks to the kind people at Polydron for giving Katie some pentagons - http://www.polydron.com/