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Darts can be thrown at random points onto the square with corners (1,1) and (−1,−1). If the dart lands inside the unit circle (that is, the circle with center (0,0) and radius 1), it is a hit. Otherwise it is a miss. The proportion of hits to tries is one quarter of π.
Below is graphical representation.
It takes a while to run this simulation to determine an approximate value for π. Wright a program using a for loop or a while loop that can run 100,000 dart throws more quickly.
This works since the ratio of the Area of a circle divided by the Area of the square is pi*r^2 / (2r)^2 = pi/4. The ratio of the darts that land in the circle of radius 1 divided by the darts in the area of the square should be the same ratio, pi/4 (if we throw enough random darts!). So 4 times this proportion is pi!