“Parity” is the mathematical concept of “evenness” and “oddness.” For example, we know that all whole numbers are either odd or even, and that if you add or subtract evens and odds, certain forms of parity will emerge. For example, if you add two odd or even numbers, you will end up with an even number; if you add an even and an odd, you’ll end up with an odd number. To make things more interesting, if you add an odd number of even numbers (say, 2 + 4 + 6), you’ll end up with an even number. How