Consider the following experiment. You draw a square, of width 1 foot, on the floor. Inside the square, you inscribe a circle of diameter 1 foot. The circle will just fit inside the square. You then throw a dart at the square in such a way that it is equally likely to fall on any point of the square. 

What is the probability that the dart falls inside the circle?

How might this process be used to estimate the value of ?