4:30

a 2500 year old geometry problem.

7:18

How large is the blue ▲

6:18

An 1800s Japanese circle problem!

4:38

A tricky problem with a "divine" answer!

7:59

a hidden triangle...

14:56

How big can y be?

8:21

calculus teacher vs "I know it already" student

16:53

EL JUEGO DE LA VIDA DE CONWAY