This example calculates pi to an arbitrary number of digits.

Computers were used in the 20th century to calculate pi and its value was known to one billion decimals places by 1989.

One reason to accurately calculate pi is to test the performance of computers.

And while he's doing that, he can also be calculating pi to the fiftieth decimal place.

A computer, you see, can calculate pi to twenty thousand places but can't work out that time always moves forward.

The latest methods of calculating pi have been proven to be fairly close to the best possible.

There are ways to calculate pi that have nothing to do with circles.

Below is a 1988 entry which calculates pi by looking at its own area:

He is responsible for calculating pi; that alone would have assured him a place in the annals of history.

Chinese mathematicians had already calculated pi by the third century before Christ.