Skip to content

Regular polygons with whole-degree interior angles

Question

For how many integers n≥3n\ge3 does a regular polygon with nn sides have an interior angle that is a whole number of degrees?

Short answer

2222. The interior angle is 180−360n180-\tfrac{360}{n}, an integer exactly when n∣360n\mid360. Since 360=23⋅32⋅5360=2^3\cdot3^2\cdot5 has 2424 divisors, removing n=1n=1 and n=2n=2 leaves 2222.

Adapted from QuantQuestions.io; question and answer rewritten by SelfMadeQuant.com.

See the hint and the full worked solution in the question bank (free account).

Open the worked solution