Pi is a number that is just a little bigger than 3.14. It is the number you get if you divide the circumference of any circle by its diameter. It's the same for ALL circles.
But it turns out to be an "irrational number," meaning its exact value is inherently unknowable. The decimal goes on forever, without repeating, for more than a trillion places.
Archimedes was the first to attempt to pinpoint the value of π around 250 B.C.Mathematicians began using the Greek letter π in the 1700s. Introduced by William Jones in 1706, use of the symbol was popularized by Leonhard Euler, who adopted it in 1737. An eighteenth-century French mathematician named Georges Buffon devised a way to calculate pi based on probability.