# (10 points) (a) For every positive integer n, prove that if n is not divisible by 3, then n2 mod 3 = 1. (b) For every positive integer n, prove that if n is odd

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(10 points) (a) For every positive integer n, prove that if n is not divisible by 3, then n2 mod 3 = 1. (b) For every positive integer n, prove that if n is odd, then n2 mod 8 = 1.