Question
Prove that if n is an odd positive integer, then 1 ≡ n2 (mod 4).
Answers
Steve
n = 2k+1
n^2 = 4k^2+4k+1 = 4(k^2+k) + 1
n^2 = 4k^2+4k+1 = 4(k^2+k) + 1