What is the formula for the sum of the interior angles of an octagon?

The formula for the sum of the interior angles of an octagon is:

Sum = (n - 2) * 180
where n is the number of sides of the polygon. In the case of an octagon, n = 8, so the formula becomes:
Sum = (8 - 2) * 180 = 6 * 180 = 1080

Therefore, the sum of the interior angles of an octagon is 1080 degrees.