Missing Addends With Three Numbers Worksheets for 1st Grade
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Prints on one US Letter page; the answer key is a separate page. Print at 100% / "Actual size" on US Letter paper. Free for personal and classroom use. Version 1 of 10. Choose another version.
Skill: Finding the unknown number in addition equations with three addends and sums up to 20
Teaching tips and what to try next
A good match for first graders who add three small numbers easily and know missing addends with two numbers from Missing Addends Within 20. Covering the blank with a sticky note and asking what is hiding under it makes the problem feel like a puzzle. Next, try the stories in Word Problems With Three Numbers or the standard page at 1.OA.D.8.
10 versions, each with its own answer key
Same skill and layout, a fresh set of problems in every version, so children can keep practicing without repeating a page. Problems are not repeated between versions unless a skill has only a small number of possible problems (for example, the addition facts within 10).
- Version 1: Sheet · Key · Both
- Version 2: Sheet · Key · Both
- Version 3: Sheet · Key · Both
- Version 4: Sheet · Key · Both
- Version 5: Sheet · Key · Both
- Version 6: Sheet · Key · Both
- Version 7: Sheet · Key · Both
- Version 8: Sheet · Key · Both
- Version 9: Sheet · Key · Both
- Version 10: Sheet · Key · Both
Download all 10 versions (one PDF)All 10 answer keys (PDF)
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About this worksheet
Once first graders can add three numbers, a good next challenge is to find a missing number in a three-number equation, such as 4 + ___ + 3 = 12. Children have to combine the two numbers they know, then think about how many more make the total. First graders are expected to find unknown numbers in addition equations, and this first-grade worksheet stretches that idea to three addends.
The page has sixteen equations in two columns. Each one adds three numbers from 1 to 9, and the totals go from 6 to 20. The empty space moves around: sometimes the first number is missing, sometimes the middle one and sometimes the last. Because the blank is not always at the end, children have to read the whole equation before they start. Each of the ten versions has new equations and its own answer key.
How to use it: show your child that the order of adding does not change the total, so they can add the two known numbers first, wherever they are. If 4 and 3 are known, that makes 7, and then the question is what goes with 7 to make 12. Counting on from 7 with fingers, or using a number line, works well. Ask your child to check each answer by adding all three numbers.
The answer key gives every missing number. For three numbers with no blank, try our Adding Three Numbers worksheet. For two numbers, try our Missing Addends Within 20 worksheet.