Subtraction & Addition Fact Families

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What is a 'fact family' in math?

A fact family is a set of related addition and subtraction facts that use the same three numbers.

If you know $$4 + 5 = 9$$, what are the two subtraction facts in its fact family?

$$9 - 5 = 4$$ and $$9 - 4 = 5$$

The numbers in a fact family are $2$, $6$, and $8$. Write one addition fact and one subtraction fact.

Addition: $2 + 6 = 8$ (or $6 + 2 = 8$). Subtraction: $8 - 6 = 2$ (or $8 - 2 = 6$).

Given $9 - 3 = 6$, what is a related addition fact?

$$6 + 3 = 9$$ or $$3 + 6 = 9$$

How can you use addition to solve $$7 - 5 = ?$$

Think, "What number plus $5$ equals $7$?" Since $5 + 2 = 7$, the answer is $2$.

Use addition to solve: $$10 - 4 = ?$$

$$6$$, because $4 + 6 = 10$.

Use addition to solve: $$8 - 3 = ?$$

$$5$$, because $3 + 5 = 8$.

What is the missing number in this family? $3 + 5 = 8$, so $$8 - 5 = ?$$

$$3$$

What is the missing number in this family? $? + 4 = 9$, so $$9 - 4 = ?$$

$$5$$

The parts are $4$ and $2$. What is the whole?

The whole is $6$, because $4 + 2 = 6$.

The whole is $9$ and one part is $7$. What is the other part?

The other part is $2$, because $9 - 7 = 2$.