I missed this on pi day, but a couple of years back I learned about this (to me) novel way of computing pi by counting collisions between moving blocks:
https://www.youtube.com/watch?v=6dTyOl1fmDo
I woke up this morning and coded up a simple simulation of this, before I had coffee, but after I took muscle relaxers for my spasming back. I'm shocked that I got the conservation of momentum and kinetic energy right the first try.
