Grade 1 math worksheet featuring 20 column addition problems with 2-digit and 1-digit numbers where students must find the missing number.

Here are the missing numbers for each problem. I have checked each calculation carefully.

1) $54 - 54 = 0$
The missing number is 0.

2) $66 - 1 = 65$
The missing number is 65.

3) $35 - 2 = 33$
The missing number is 33.

4) $18 - 17 = 1$
The missing number is 1.

5) $80 + 8 = 88$
The missing number is 88.

6) $4 + 1 = 5$
The missing number is 5.

7) $72 - 1 = 71$
The missing number is 71.

8) $7 - 5 = 2$
The missing number is 2.

9) $31 - 1 = 30$
The missing number is 30.

10) $28 - 7 = 21$
The missing number is 21.

11) $78 - 75 = 3$
The missing number is 3.

12) $37 - 34 = 3$
The missing number is 3.

13) $74 - 72 = 2$
The missing number is 2.

14) $42 + 3 = 45$
The missing number is 45.

15) $19 + 0 = 19$
The missing number is 19.

16) $46 - 1 = 45$
The missing number is 45.

17) $17 - 0 = 17$
The missing number is 17.

18) $17 - 12 = 5$
The missing number is 5.

19) $28 - 20 = 8$
The missing number is 8.

20) $64 + 2 = 66$
The missing number is 66.

Final Answer:
1) 0
2) 65
3) 33
4) 1
5) 88
6) 5
7) 71
8) 2
9) 30
10) 21
11) 3
12) 3
13) 2
14) 45
15) 19
16) 45
17) 17
18) 5
19) 8
20) 66