Fact Families: Addition & Subtraction — Answer Key
Part A: Complete the Fact Family Equations
Solve each equation. Write the answer on the line.
3
+7
10
7
+3
10
10
-3
7
10
-7
3
4
+6
10
6
+4
10
10
-4
6
10
-6
4
Part B: Fill in the Missing Number
Read each sentence. Write the missing number on the line.
1. The fact family for 3, 7, and 10 has 4 equations.
Every fact family with 3 different numbers has 4 equations: 2 addition and 2 subtraction.
2. If 4 + 6 = 10, then 10 - 6 = 4.
Since 4 + 6 = 10, the inverse subtraction gives 10 - 6 = 4.
3. If 7 + 3 = 10, then 10 - 3 = 7.
Since 7 + 3 = 10, subtracting 3 from 10 gives back 7: 10 - 3 = 7.
4. The numbers 4, 6, and 10 form a fact family.
4 + 6 = 10, so the numbers 4, 6, and 10 form a fact family.
5. 3 + 7 = 10, so 10 - 7 = 3.
Since 3 + 7 = 10, subtracting 7 from 10 gives back 3: 10 - 7 = 3.
Part C: True or False
Read each statement. Write True or False.
1. 3 + 7 = 10 and 10 - 7 = 3 are in the same fact family.
True False
True — these two equations use the same three numbers 3, 7, and 10.
2. The numbers 4, 5, and 10 form a fact family.
True False
False — 4 + 5 = 9, not 10, so these three numbers do not form a fact family.
3. Every fact family with three different numbers has four equations.
True False
True — a fact family with three different numbers always has 2 addition and 2 subtraction equations, totaling 4.