Mathematical parity is usually one of the first rules learned in early arithmetic classes, though you might be unfamiliar with the name. It is how we split up all integers into two categories: even numbers and odd numbers. Determining the parity of an integer—a number that can be written without a remainder or fractional component—is as simple as asking one question: Is the number divisible by 2? If yes, then it is even; if no, then it is odd.
So where exactly does 0 fall into these categories? Most people are confused by the number 0, unsure if it’s an integer to begin with and unaware of its placement as a number, because it technically signifies an empty set. Under the rules of parity, is zero even or odd?
As a whole number that can be written without a remainder, 0 classifies as an integer. So to determine whether it is even or odd, we must ask the question: Is 0 divisible by 2?
A number is divisible by 2 if the result of its division by 2 has no remainder or fractional component—in other terms, if the result is an integer. Let’s break that down. When you go about dividing a number, each part of an equation has a specific purpose and name based on what it does. For example, take a simple division by two: 10÷2=5. In this division statement, the number 10 is the dividend, or the number that is being divided; the number 2 is the divisor, or the number by which the dividend is divided; and the number 5 is the quotient, or the result of the equation. Because the quotient of this division by 2 is an integer, the number 10 is proved to be even. If you were to divide, say, 101 by 2, the quotient would be 50.5—not an integer, thereby classifying 101 as an odd number.
So, let’s tackle 0 the same way as any other integer. When 0 is divided by 2, the resulting quotient turns out to also be 0—an integer, thereby classifying it as an even number. Though many are quick to denounce zero as not a number at all, some quick arithmetic clears up the confusion surrounding the number, an even number at that.