Identity Property of Addition: Definition & Example

This lesson will give you the definition of the identity property of addition. You will be shown examples to clearly illustrate the material. Following the lesson will be a brief quiz to test your knowledge.
Identity Property of Addition Defined
When you think of the word identity, you may think about who or what a person or thing is. You may think about an identification card, like a driver’s license, that has your picture and some basic description information. You may also think of things like identity theft, where others can steal all of your information and thus, your identity.

But in mathematical addition, an identity takes on a different meaning. In math, an identity is a number, n, that when added to other numbers, gives the same number, n. The additive identity is always zero. This brings us to the identity property of addition, which simply states that when you add zero to any number, it equals the number itself.

Before getting into more about this property, let’s first go over some vocabulary related to addition. When you add two or more numbers together, those numbers are called addends. A sum is what you get when you add two or more addends together.

The Identity Property of Addition
Okay, now that we know those vocabulary terms, let’s look at a quick example of how the property works. If you add the numbers, or addends, 8 + 0, the sum is 8. The addend 8 did not have to change his identity when added with 0; it stayed the same. But, if we used any other number to add to 8, we would get a different sum. Let’s take a look:

8 + 1= 9 (not 8)
8 + 2 = 10 (not 8)
8 + -5 = 3 (not 8)

I think you get the point by now!

Examples of the Identity Property of Addition
In the identity property of addition, a number is always being added to zero. The sum is always that number. Let’s look at some examples:

10 + 0 = 10
0 + 24 = 24
175 + 0 = 175
-6 + 0 = -6

As you can see, the property even applies to zero added to negative numbers: -6 + 0 = -6

100,000,000,000,000,000,000 + 0 = 100,000,000,000,000,000,000

One incredibly huge number plus zero equals one incredibly huge number. It doesn’t matter how long the number is that you are adding to zero; the sum will still be that number.

Why does the identity property of addition always work? Well, think about a real life example:

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