product of two consecutive integers is even

Can someone prove for me that n(n + 1) where n is an arbitrarily chosen integer can be represented as 2k where k is an integer? It was on the board today, and apparently I need to know it, but I was sleeping.

>>2
You didn't answer your own question...

if n is even, n(n+1) = 2*((n/2)(n+1)). if n is odd, n(n+1) = 2*(n((n+1)/2)).