Algodoo

this was inspired by 3Blue1Brown's video about using perfect elastic collisions to compute PI (the title of the video is "The most unexpected answer to a counting puzzle") in this setup it should compute 5 digit's but due to floating point errors it seems to only have an accuracy of 4 digits I suggest changing the play speed to ten also the rod and sliders holding the blocks in place should have no effect as the sliders are almost massless so you don't have to worry about them effecting the results too much.

*edit*

I moved the blocks closer so now it is quicker I also managed to make it display the decimal value (was a slight pain I had to mess around trying to make it give the decimal value) and for some reason it became more accurate when I moved them closer together I have no idea why

*edit 2*

I attempted to make it more accurate by scaling the size up and decreasing the velocity further now it is slightly under (masses were perserved)