JAMB 1983 · UME · Q3

Given a regular hexagon, calculate each interior angle of the hexagon.

Worked solution (try it first)

The exterior angles of any polygon add up to $360^\circ$ , so each exterior angle of a regular hexagon is $360^\circ \div 6 = 60^\circ$ .
An interior angle and its exterior angle lie on a straight line, so the interior angle is $180^\circ - 60^\circ = 120^\circ$ , option C.