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Missing Addends - Worksheet 9 - 1st Grade

Hard

Find the missing number in addition equations (Hard)

23 problems · 10-15 minutes · Skills: addition, algebraic thinking

About This Worksheet

This hard-level worksheet contains 23 problems designed for 1st Grade students practicing missing addends. Hard worksheets feature challenging problems including multi-step questions, missing values, and real-world applications to push students further.

Missing addend problems introduce algebraic thinking — finding an unknown value. This prepares students for equation solving in later grades.

How to Solve: Worked Example

Example Problem: ___ + 8 = 17
Solution Steps:
  1. The missing number is on the left side.
  2. Use subtraction: 17 − 8 = 9.
  3. Check: 9 + 8 = 17. Correct!
Answer: 9
Tip: It doesn't matter which side the blank is on — always subtract the known part from the total.
1
13 + ___ = 20
2
___ + 4 = 12
3
11 + ___ = 17
4
___ + 7 = 13
5
___ + 4 = 12
6
6 + ___ = 14
7
15 + ___ = 18
8
14 + ___ = 17
9
5 + ___ = 14
10
3 + ___ = 14
11
___ + 4 = 13
12
___ + 6 = 16
13
___ + 5 = 16
14
___ + 10 = 20
15
8 + ___ = 12
16
___ + 10 = 19
17
___ + 14 = 19
18
___ + 9 = 17
19
7 + ___ = 16
20
9 + ___ = 15
21
___ + 3 = 16
22
14 + ___ = 20
23
___ + 7 = 16

Answer Key

1. 72. 83. 64. 65. 86. 87. 38. 39. 910. 1111. 912. 1013. 1114. 1015. 416. 917. 518. 819. 920. 621. 1322. 623. 9

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How many problems are on this worksheet?

This worksheet contains 23 problems. It typically takes 10-15 minutes to complete. An answer key with all solutions is included.