Where this tool comes from
Buffon’s needle and Monte Carlo
In 1733 the French naturalist Georges-Louis Leclerc, Comte de Buffon, asked how likely a needle dropped on a floor of parallel boards is to cross a crack. He published the answer in 1777, and π is in it. In the 1940s Stanislaw Ulam and John von Neumann made random sampling a working method and called it Monte Carlo.
One thing to hold: Throw darts at random at a square with a circle drawn inside it, and count how many land in the circle.
Why it matters: The share of darts inside the circle estimates the circle’s share of the square, π/4. More darts pin π down, but slowly: to halve the typical error you need four times as many darts.