Question

How to calculate the sum of interior angles of 10 sided polygon

Answer 1

there is a formula for this but you can do it by working out the exterior angle of a regular polygon - the sum of these = 360 degrees for any polygon.
so for a 10 sided polygon ext angle = 360 / 10 = 36 and so the interior angle will be 180-36 = 144 degrees
Sum of all interiors = 144 * 10 = 1440 degrees

Answer 2

The formula for the sum of the interior angles of a n-sided polygon is: (n - 2) * 180 n = 10 (10-2) * 180 = 8 * 180 = 1440 degrees.