Puzzles
Drop a needle again and again, and pi falls out
Rule a floor with parallel lines spaced exactly as far apart as a needle is long. Drop the needle randomly, over and over, and record how often it crosses a line. What does the fraction of crossings converge toward?
Reveal the answer
It converges to 2/π, so counting enough crossings gives an experimental way to estimate pi from pure chance. Georges-Louis Leclerc, Comte de Buffon, devised the problem in 1733 and published the solution in 1777, making it one of the earliest results in geometric probability.
— Georges-Louis Leclerc, Comte de Buffon, Essai d'arithmétique morale — 1777 (problem devised 1733)