Explanation:
Let (2n +1) be the larger odd number by definition, where n can be any real integer. Then (2n - 1) is the smaller consecutive odd number.
The product of the 2 odd numbers is (2n + 1)(2n - 1) = 4n^2 - 1 = 2(2n^2) - 1. Since n^2 must be an integer, 2(2n^2) - 1 is odd. (Shown)