A few hundred years ago people enjoyed betting on coins tossed on to the floor ... would they cross a line or not?
A man (Georges-Louis Leclerc, the Count of Buffon) started thinking about this and worked out the probability to approach π (Pi). It is called "Buffons Needle" in his honor.
This app is a simulator based on one of the oldest problems in geometrical probability approximates Pi. Put other words, estimating Pi by Dropping Sticks.