Press the flag to immediately start the simulation. It will randomly place a dot on the red and blue image on the left and detect which color it touches. It then uses that data to calculate pi. The graph on the right shows how close it is to pi.
I saw some people calculate pi by throwing darts at something like the symbol on the left and thought it would be cool to see a computer do it. I could make the simulation faster, but then it would be hard to see its progress.
