What is the product of two even numbers?

The product of two even numbers is always an even number.

Here is the proof:

We define an even number as a number of the form 2n for some integer n.

Now let 2n be one even number and 2m be another.

The product is (2n)(2m)=2(2mn) and of course 2mn is an integer since the integers are closed under multiplication. Hence, 2(2mn) is an even number.