Fact Families: Addition & Subtraction — Answer Key
Part A: Complete the Fact Family
Write the missing number to complete each equation.
1. 6 + 9 = 15
In the fact family for 6, 9, and 15, 6 + 9 = 15.
2. 9 + 6 = 15
In the fact family for 6, 9, and 15, addition can be done in either order: 9 + 6 = 15.
3. 15 - 6 = 9
In the fact family for 6, 9, and 15, subtraction is the inverse of addition: 15 - 6 = 9.
4. 15 - 9 = 6
In the fact family for 6, 9, and 15, 15 - 9 = 6.
5. 8 + 9 = 17
In the fact family for 8, 9, and 17, 8 + 9 = 17.
6. 9 + 8 = 17
In the fact family for 8, 9, and 17, addition can be done in either order: 9 + 8 = 17.
7. 17 - 8 = 9
In the fact family for 8, 9, and 17, subtraction is the inverse of addition: 17 - 8 = 9.
8. 17 - 9 = 8
In the fact family for 8, 9, and 17, 17 - 9 = 8.
9. If 7 + 9 = 16, then 16 - 7 = 9.
Since 7 + 9 = 16, subtracting 7 from 16 gives back 9: 16 - 7 = 9.
Part B: Match the Fact Family Partners
Draw a line from each addition fact to its subtraction partner.
1. Match each addition fact to its subtraction partner.
5 + 8 = 13
→ 13 - 8 = 5
11 - 5 = 6
7 + 9 = 16
→ 16 - 9 = 7
12 - 4 = 8
6 + 5 = 11
→ 11 - 5 = 6
16 - 9 = 7
8 + 4 = 12
→ 12 - 4 = 8
13 - 8 = 5
5 + 8 = 13 pairs with 13 - 8 = 5 (fact family 5, 8, 13). 7 + 9 = 16 pairs with 16 - 9 = 7 (fact family 7, 9, 16). 6 + 5 = 11 pairs with 11 - 5 = 6 (fact family 5, 6, 11). 8 + 4 = 12 pairs with 12 - 4 = 8 (fact family 4, 8, 12).