How do people find digits of pi?

Pi is the ratio of C/2r where C is the circumference and r is the radius. No matter what circle you look at, this ratio will always remain the same number, which is pi. Now if one was to look at the circle of radius 1, you would only need to calculate the length of the circumference and divide it by two. Since you can always measure in smaller and smaller increments, you can always come up with more and more numbers to add to the length of the circumference and thus come up with more and more digits of pi.

To find the actual values of the digits of pi, search for "digits of pi" on any internet search site.

Actually, there are a number of infinite series that add to pi or to a function of pi. These are used to calculate pi to very high degrees of accuracy.