Question

You are given the measure of each interior angle of a regular n-gon. find the value of n

Answer 1

Number of Sides = 360 / (180 - EACH Interior Angle)

So, for example, if each interior angle equals 108 degrees then the polygon has five sides.

Number of Sides = 360 / (180 -108)
Number of Sides = 360 / 72
Number of Sides = 5

Source
http://www.1728.org/polygon.htm