π, the Greek letter pi, is a special number often used in calculations involving circles.
The diameter of a circle, if wrapped around the outside of the circle, would fit just over three times (π times). If the circumference of any circle is divided by its diameter the answer is just over 3.
A more exact value of π is approximately 3.14 (to 2 d.p.). The fraction with the closest value to pi is ^{22}⁄_{7} or 3^{1}⁄_{7}
Calculators and computers can work out PI to a huge number of decimal places.
π = 3.141592653589793238462633832
