We know PI as the ratio between a circle’s circumference and its diameter.
It is so much more..
> Pi cannot be represented in a formula as a fraction > Its fractional digits never repeat > If a straight line represents simplicity and measurability, Pi represents the complexity and the irrational side of nature. > Unless you are travelling in a straight line, Pi will feature in your travel equations > Pi is an important and ubiquitous constant and appears in all areas of science