Use addition and subtraction fact families

A fact family connects three numbers in a part–part–whole relationship through two addition equations and two related subtraction equations, such as $7+5=12$ , $5+7=12$ , $12-7=5$ , and $12-5=7$ , typically with numbers and sums within 20. This establishes subtraction as the inverse of addition, while clarifying that addition can change order but subtraction cannot, supporting flexible calculation and later equation reasoning.

Detailed Explanation: Use addition and subtraction fact families

A fact family uses two parts and one whole.

For example, suppose the parts are $6$ and $3$ . The whole is $9$ , because $(6+3=9)$ .

Write the four related facts:

6+3=9

3+6=9

9-6=3

9-3=6

Here is how to remember them:

Add the two parts to make the whole: $(6+3=9)$ .
Switch the parts in addition: $(3+6=9)$ . The sum stays the same.
Start with the whole and subtract one part: $(9-6=3)$ .
Start with the whole and subtract the other part: $(9-3=6)$ .

Addition can change order, but subtraction cannot. For example, $(6-3=3)$ , but $(3-6)$ does not show this fact family.

Learn by doing: Use addition and subtraction fact families

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Fact Family - Addition - Triangle to Fact

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Use addition and subtraction fact families

Detailed Explanation: Use addition and subtraction fact families

Learn by doing: Use addition and subtraction fact families

Practice with unlimited practice problems

Practice:

Fact Family - Addition - Triangle to Fact