500
Sasha was stumped on a math question. She knew that the shape she was staring at was an octagon. The sides were congruent, as well as the angles. The question was asking her to figure out the sum of the interior angles, but she just couldn't remember how to figure it out. Starting with a triangle, list the sum of the interior angles for each shape up to an octagon.
tri- 180, Quad- 360, P- 540, Hex- 720, Hep- 900, Oct- 1,080