Addition Within 20 — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. 8 + 3 = 11
Make a ten: 8 + 2 = 10, then 10 + 1 = 11.
2. 7 + 5 = 12
Make a ten: 7 + 3 = 10, then 10 + 2 = 12.
3. 6 + 7 = 13
Make a ten: 7 + 3 = 10, then 10 + 3 = 13.
4. 9 + 5 = 14
Make a ten: 9 + 1 = 10, then 10 + 4 = 14.
5. 8 + 7 = 15
Make a ten: 8 + 2 = 10, then 10 + 5 = 15.
6. 9 + 7 = 16
Make a ten: 9 + 1 = 10, then 10 + 6 = 16.
7. 8 + 9 = 17
Make a ten: 9 + 1 = 10, then 10 + 7 = 17.
8. 9 + 9 = 18
9 + 9 = 18. This is a doubles fact: 9 plus 9 equals 18.
9. 5 + 6 = 11
Start at 5 and count on 6 more to reach 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.
6 + 6
→ 12
12
7 + 8
→ 15
15
9 + 4
→ 13
13
5 + 9
→ 14
14
Each addition fact has one correct sum: 6 + 6 = 12 (doubles); 7 + 8 = 15; 9 + 4 = 13; 5 + 9 = 14.