Darts land at random on a square. The circle covers exactly π/4 of that square — so four times the share that lands inside is π, no geometry required.
square 2 × 2 · circle radius 1 · a dart is inside when x² + y² ≤ 1
The shaded band is where the estimate should usually land. Ten times more accuracy costs a hundred times more darts.
space pause · t throw 10k · r reset