# What is the Pi number for?

**π** is defined as the ratio of the circumference of a circle to its diameter. It is used to **calculate the perimeter and area of a circle** . It is **roughly equal to 3.1416,** but actually researchers estimate it to be more than 12 trillion decimal places.

It is an irrational and transcendent number (not algebraic). It is used primarily in geometry, but also in probability, statistics, and other aspects of mathematics.

The number Pi remains a mystery to scientists and the subject of much research. And while it is useless to memorize the , many records have been broken!