Answer: 1080
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Explanation:
We have an octagon because there are n = 8 sides. The diagram below shows one way to number the sides so you can count them efficiently (without missing any or double counting any).
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Plug n = 8 into the formula below
S = 180(n-2)
S = 180(8-2)
S = 180(6)
S = 1080
The 8 interior angles add up to 1080 degrees.
