addend
A number that is being added to other numbers.
An addend is any number being added together in an addition problem. When you solve 5 + 3 = 8, both the 5 and the 3 are addends. The answer, 8, is called the sum.
You can have as many addends as you want in a single problem. In 2 + 4 + 7 + 1 = 14, there are four addends, and they all combine to make the sum of 14. Whether you're adding two numbers or twenty, each number you're combining is an addend.
Mathematicians use specific words like addend, sum, factor, and product because precision matters when explaining how math works. When your teacher asks you to identify the addends in a problem, she wants you to point out which numbers are being added together, not the final answer.
Think of addends as ingredients going into a recipe. Just as flour, sugar, and eggs are separate ingredients that become a cake, addends are separate numbers that become a sum.