Addition, missing numberUp to 20
Name: Date:
12 + = 10
22 + = 18
3 + 11 = 13
4 + 4 = 14
517 + = 19
60 + = 2
75 + = 10
8 + 16 = 19
93 + = 20
106 + = 19
Missing addends worksheets
A missing addend turns addition into a question about what is not there yet. These free printable worksheets hide one of the two addends within twenty, so a child has to work out the gap rather than read off a total.
If they get stuck
Missing addends
The answer key prints on a separate page.
What's on this sheet
Filling 7 + __ = 15 is the same relationship as 15 − 7, met from the other direction. That is exactly why it matters: children who only ever practice addition forwards treat subtraction as an unrelated topic, while children who fill gaps start to see the two as one fact family seen from different sides.
Why this sheet works
It is also the algebra a six-year-old can actually do. The blank is an unknown, and finding it means undoing an operation — the same move that later becomes solving for x, minus the notation. Sheets here keep the numbers within twenty so the reasoning, not the arithmetic, is the hard part.
How this one works
One question from a sheet like this one, worked a step at a time — with a sentence saying what just happened and why.
Missing addends, step by step