How many digits are in pi?

An endless number of digits are in pi. It is an irrational number, which means it cannot be expressed as the ratio of any two integers. Furthermore, it was proved in 1882 that pi is not the root of an algebraic equation that has rational factors.

Pi is the ratio of a circle's circumference to its diameter. This value holds regardless of the size of the circle. As of 2014, the greatest number of digits calculated for pi is more than 206 billion by a Tokyo-based supercomputer. The Greek philosopher and mathematician Archimedes is the first recorded person to calculate pi.