n^2-n = even
Factor n^2-n:
n(n - 1)
We have one of two scenarios:
Factor n^2-n:
n(n - 1)
We have one of two scenarios:
- If n is odd, then n - 1 is even. The product of an odd and even number is an even number
- If n is even, then n - 1 is odd. The product of an even and odd number is an even number