Finding the Missing Number in a Fact Family

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$$ ? \times 5 = 20 $$

The missing number is $4$. You can find this by using the inverse operation: $20 \div 5 = 4$.

$$ 3 \times ? = 21 $$

The missing number is $7$. You can find this by using the inverse operation: $21 \div 3 = 7$.

$$ 45 \div ? = 9 $$

The missing number is $5$. You can find this by thinking of the related multiplication fact: $9 \times 5 = 45$.

$$ ? \div 6 = 7 $$

The missing number is $42$. You can find this by using the inverse operation: $6 \times 7 = 42$.

The members of a fact family are $8$, $9$ and an unknown number. What is the unknown number?

The missing member is $72$, because $8 \times 9 = 72$.

The members of a fact family are $7$, $?$, $42$. What is the missing number?

The missing member is $6$, because $42 \div 7 = 6$.

$$ 64 \div 8 = ? $$

The missing number is $8$, because $8 \times 8 = 64$.

If you have the equation $54 \div 6 = 9$, which multiplication fact helps you check your answer?

$6 \times 9 = 54$ or $9 \times 6 = 54$.

Use the inverse operation to solve for the unknown value $n$ in $n \times 8 = 32$.

To find $n$, you can use division: $n = 32 \div 8$. So, $n = 4$.

The numbers in a fact family are $12$, $7$ and $84$. Write an equation to find the value of $84 \div 7$.

The related multiplication fact is $7 \times 12 = 84$. Therefore, $84 \div 7 = 12$.

$$ 72 \div ? = 9 $$

The missing number is $8$. You can think $9 \times ? = 72$.

What is the missing number in this series from the same fact family: $4 \times 5 = 20$, $20 \div 5 = 4$, $5 \times 4 = ?$

The missing number is $20$. The complete fact is $5 \times 4 = 20$.