Fact family

A collection of related addition and subtraction facts involving the same numbers. Most addition and subtraction fact families include two addition and two subtraction facts. For example, the addition/subtraction fact family for the numbers 2, 4, and 6 consists of the following: 2 + 4 = 6, 4 + 2 = 6 and 6 - 4 = 2, 6 - 2 = 4. Fact families involving doubles facts consist of only two facts. For example, the addition/subtraction fact family for the numbers 7, 7,and 14 consists of the following: 7 + 7 = 14, 14 - 7 = 7.