This Pi Day, try calculating everyone’s favourite mathematical constant using balls and a cardboard tube, thanks to a mathematical trick involving the balls’ masses ...

For thousands of years people have struggled to pin down pi. Watch how mathematicians from Archimedes on have wrapped their heads around the math of circles.

Outside the US, Pi Day should probably be July 22 (22/7)—this fraction is a surprisingly good estimate of pi. You can find the value of pi with a mass and a spring.