math
posted by stephanie .
explain how we use pi in the real world.

If I want to add fringe around a circular rug, I'd measure the diameter and multiply it by pi to find the amount of fringe I'd need.

or
In the recent Olympic Games in China you probably noticed that in some of the races they had a staggered starting position for the 200m and 400 m races
Since the different lanes in the circular paths have different radii, the value of pi has to be used to calculate that stagger so that each runner covers the same linear distance.