Π, the Greek symbol for Pi, is an irrational number and more distinctively known as a transcendental number. It is a fractional number, obtained by dividing circumference of a circle by its diameter. A close approximation that many schools teach is 22⁄7, which is around 3.14.
The Pi ratio holds true for all circles of any size.
Circle, is the most efficient shape possible.
Energy can be minimised by taking a circular or spherical form.
Pi number has been calculated up to ten trillion digits, without any repeating pattern.