Buffon's Needle — finding π by dropping sticksRule a floor with evenly spaced lines and toss matchsticks onto it at random. Count how many land across a line. The catch: that fraction depends on π, so with enough throws the sticks themselves compute the circle’s number — no circle in sight.For a needle as long as the gap, the chance of a crossing works out to exactly 2/π (Buffon, 1733). Flip it around: π ≈ 2 × (throws) / (crossings). It converges slowly — error shrinks like 1/√N — but it converges.