Calculating the ratio of a circle's circumference to its diameter is as easy as pi.
Today is Pi Day, an event that celebrates this mathematical constant.
This date was chosen because 3, 1 and 4 are the first three significant figures of pi (π) when it is written out.
Pi is an irrational number, which means that it can't be written as a fraction.
When written out, its decimal representation goes on infinitely without repeating.
The oldest attempts to calculate pi date back to ancient Babylon and Egypt, around 1,900 BCE.
