What is a Fact Family in Math?

In a mathematical equation, all the numbers included in the equation are considered to be a family and can inter-relate. For example, 2 + 3 = 5; as a family, these numbers can relate in other ways. 5 – 2 = 3, 5 – 3 = 2, 2 + 3 = 5, 5 – 3 = 2. 2, 3, and 5 are the numbers included in the family.