Pi

The ratio of the circumference of a circle to its diameter. The ratio itself has a value, when taken to eight decimal places, of 3.14159265, or 22 divided by 7. For the wire and cable industry, this ratio can be used to calculate the diameter of each strand of wire in the cable to provide a defined cross sectional area. Or, vice versa, to calculate the cross sectional area that a given wire strand diameter will provide.