It's a good thing for us that we have a very useful formula we can use to find this sum. Sum of the Measure of Interior Angles = (n - 2)*180. Yes, the formula tells us to subtract 2 from n, which is the total number of sides the polygon has, and then to multiply that by 180. We can check this formula to see if it works out. We know that the angles of a triangle will always add up to 180.