Pi As A Number

Pi has been an important number throughout history, known as far back as Ancient Chinese and Greek civilizations. It it perhaps the most famous and ubiquitous number in mathematics, next to the numbers e,<i>i</i>,0, and 1. It is mathematically expressed as the ratio of any given circle's circumference to its diameter.  Its approximate value is 3.14 or 22/7, but it is an irrational number.