Adding Three Numbers — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 3 + 3 + 4: the doubles are 3 and 3
3+3=6, then 6+4=10.
2. 3 + 3 + 4 = 10
3+3=6, then 6+4=10.
3. 5 + 5 + 2 = 12
5+5=10, then 10+2=12.
4. 4 + 4 + 3 = 11
4+4=8, then 8+3=11.
5. 2 + 2 + 7 = 11
2+2=4, then 4+7=11.
6. 6 + 6 + 1 = 13
6+6=12, then 12+1=13.
7. 7 + 7 + 2 = 16
7+7=14, then 14+2=16.
8. 1 + 4 + 4 = 9
4+4=8, then 8+1=9.
9. 5 + 3 + 3 = 11
3+3=6, then 6+5=11.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
2 + 2 + 5
→ 9
9
4 + 4 + 6
→ 14
14
6 + 6 + 3
→ 15
15
5 + 5 + 8
→ 18
18
Doubles give a quick sum to build on.