Question 130236
There is a formula... the sum of the measures of the interior angles of a convex n-gon is (n-2)180 degrees.  For a triangle, n=3, so it's (1)180=180 degrees.  For a quadrilateral, it's (4-2)180=(2)180=360 degrees.  For a pentagon, it's (5-2)180=(3)180=540 degrees.  So plug in n=13 to see the sum of the angle measures for a 13-sided polygon.