Regular Exterior Angles

In a regular polygon the exterior angles are all equal too, so the full turn is shared equally: each exterior angle of a regular polygon with n sides is 360 ÷ n.

A regular hexagon turns through 360° in six equal turns: $\frac{360}{6} = 60$ degrees each. Its interior angle is then $180-60 = 120$ degrees, the same answer the angle sum gave. On the board, the equal arcs together with Exterior angles of a polygon fix each exterior angle.