Related facts in math

Related facts are a group of addition and subtraction facts, or multiplication and division facts, that use the same three numbers. They are the facts in a fact family. For 4, 9 and 13, the related facts are 4 + 9 = 13, 9 + 4 = 13, 13 − 4 = 9 and 13 − 9 = 4.

What is a related fact in math?

Two facts are related when they use the same numbers and one can be used to find the other. Textbooks use the phrase related facts where other books say fact family or family of facts. The idea is the same: addition and subtraction are linked, and so are multiplication and division.

Related facts examples

How to write related facts

1. Start with one fact, such as 8 + 5 = 13.
2. Swap the addends: 5 + 8 = 13.
3. Write the subtraction facts that start with the sum: 13 − 8 = 5 and 13 − 5 = 8.

For multiplication, start with 4 × 6 = 24, swap to 6 × 4 = 24, then write 24 ÷ 4 = 6 and 24 ÷ 6 = 4.

Practice questions

1. Write a related subtraction fact for 7 + 6 = 13.

13 − 7 = 6 (or 13 − 6 = 7).

2. Write a related addition fact for 15 − 9 = 6.

6 + 9 = 15 (or 9 + 6 = 15).

3. Write a related division fact for 5 × 7 = 35.

35 ÷ 5 = 7 (or 35 ÷ 7 = 5).

4. Write all the related facts for 3, 8 and 24.

3 × 8 = 24, 8 × 3 = 24, 24 ÷ 3 = 8 and 24 ÷ 8 = 3.

Related facts and fact families: is there a difference?

In practice, no. Some programs use related facts for the facts that share three numbers and fact families for the picture or the whole set, but the math is the same. See what a fact family is for the full explanation.

Why related facts help

• They let children check an answer with the inverse operation.
• They turn a hard fact into an easy one. Subtracting 13 − 8 is easier if you remember 8 + 5 = 13.
• They show that math facts are connected rather than separate things to memorize.

Related facts worksheets

Print related facts practice from the addition and subtraction worksheets, or the multiplication and division worksheets.