Addition within 20 — Answer Key
Part A: Solve the Addition Problems
Add the numbers. Write the answer on the line.
9
+3
12
8
+5
13
7
+6
13
9
+5
14
8
+7
15
9
+6
15
7
+9
16
8
+6
14
9
+8
17
6
+5
11
9
+7
16
8
+4
12
Part B: Fill in the Missing Number
Write the missing number to complete each number sentence.
1. 9 + 4 = 13
9 + 4 = 13. The missing addend is 4.
2. 7 + 8 = 15
7 + 8 = 15. The missing addend is 7.
3. 10 + 7 = 17
10 + 7 = 17. The missing addend is 7.
4. 10 + 6 = 16
10 + 6 = 16. The missing addend is 10.
5. 9 + 10 = 19
9 + 10 = 19. The missing addend is 10.
6. 10 + 8 = 18
10 + 8 = 18. The missing addend is 8.