Addition Within 20 — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 4 + 8 = 12
Make a ten: 8 + 2 = 10, then 10 + 2 = 12.
2. 9 + 8 = 17
Make a ten: 9 + 1 = 10, then 10 + 7 = 17.
3. 6 + 5 = 11
Start at 6 and count on 5 more to reach 11.
4. 7 + 9 = 16
Make a ten: 9 + 1 = 10, then 10 + 6 = 16.
5. 5 + 8 = 13
Make a ten: 8 + 2 = 10, then 10 + 3 = 13.
6. 6 + 9 = 15
Make a ten: 9 + 1 = 10, then 10 + 5 = 15.
7. 8 + 6 = 14
Make a ten: 8 + 2 = 10, then 10 + 4 = 14.
8. 3 + 8 = 11
Make a ten: 8 + 2 = 10, then 10 + 1 = 11.
9. 9 + 3 = 12
Make a ten: 9 + 1 = 10, then 10 + 2 = 12.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
8 + 8
→ 16
16
3 + 9
→ 12
12
7 + 7
→ 14
14
9 + 2
→ 11
11
Each addition fact has one correct sum: 8 + 8 = 16 (doubles); 3 + 9 = 12; 7 + 7 = 14 (doubles); 9 + 2 = 11.