Using the conservation of momentum, we can determine Pi through calculating collisions between two objects, one with mass 'm' and the other with mass 'm'*10^'n', where 'n+1' is the digits of Pi yielding from the collisions. The graph on the top right shows the kinetic energy of both objects plotted against each other, and the circle formed is the reason for the value Pi appearing. For a better explanation, watch 3Blue1Brown's video!