What Is a Fact Family?

By Staff WriterLast Updated Mar 31, 2020 5:47:39 AM ET

A fact family is a group of math facts that uses the same numbers. When adding or subtracting, three numbers are used to obtain four facts. A fact family helps build a conceptual understanding of how addition and subtraction work.

Generally, a fact family consists of three numbers, two of which add up to the third. The numbers are related, and they always produce at least four math facts. When working with two numbers, two possible fact families can be made. A fact family is typically used in first grade math. It helps children study basic addition and subtraction facts in an easy way. It is used to learn and reinforce the connection between the two math processes.

For example, a fact family can be formed using the numbers 4, 6 and 10. In this family of three numbers, 6 and 4 are added to get the last number, which is 10. Using the commutative property of addition, the first two numbers are switched to get the same answer. This means adding 4 and 6 will still result in 10. Considering that addition is the direct relationship among the numbers, subtraction is the family cousin through the inverse property. It is the opposite process of addition, but it is still related in the fact family. The problems involved still use only three numbers. With the process of subtraction, subtracting 4 from 10 results in 6, while subtracting 6 from 10 results in 4.