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Missing Addends - Worksheet 8 - 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
8 + ___ = 12
2
3 + ___ = 16
3
___ + 8 = 17
4
8 + ___ = 13
5
11 + ___ = 19
6
11 + ___ = 14
7
___ + 12 = 18
8
8 + ___ = 16
9
8 + ___ = 19
10
___ + 3 = 15
11
3 + ___ = 20
12
___ + 11 = 20
13
5 + ___ = 16
14
___ + 7 = 20
15
___ + 4 = 14
16
9 + ___ = 16
17
14 + ___ = 19
18
___ + 3 = 16
19
5 + ___ = 16
20
___ + 12 = 16
21
___ + 9 = 12
22
12 + ___ = 15
23
10 + ___ = 19

Answer Key

1. 42. 133. 94. 55. 86. 37. 68. 89. 1110. 1211. 1712. 913. 1114. 1315. 1016. 717. 518. 1319. 1120. 421. 322. 323. 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.