Missing Addends Within 100 Worksheets for 2nd Grade
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Skill: Finding the unknown addend with sums up to 100
Teaching tips and what to try next
Suits second graders who already solve Missing Addends Within 20 and can add two-digit numbers. Encourage jumps to the next ten first, since landing on a round number makes the rest of the gap easy to see. For the matching subtraction skill, try Two-Digit Subtraction With Regrouping, or review the standard at 2.NBT.B.5.
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
Finding a missing addend helps second graders see how addition and subtraction are connected. If 34 plus some number is 72, a student can count up from 34 or subtract 34 from 72. This second-grade worksheet gives twenty equations with one blank to fill in.
Every equation has two addends of at least 10, and each sum is between 25 and 100. The blank can be the first addend or the second addend, so children cannot just follow a pattern. Some problems need regrouping when they are solved by subtraction, and some do not. Each of the ten versions has new equations and its own answer key.
How to use it: show two strategies and let your child pick one. The first is counting up: from 34, jump 6 to 40, then 30 more to 70, then 2 more to 72, and add the jumps, 6 + 30 + 2 = 38. An open number line on scrap paper makes the jumps easy to see. The second strategy is to subtract the known addend from the sum. After each answer, have your child check by adding the two addends; if the total matches the sum, the answer is right. This check builds good habits for every kind of math problem.
The answer key shows each missing number. To build up to this sheet, try our Missing Addends Within 20 worksheet. For subtraction practice with the same number sizes, try our Two-Digit Subtraction With Regrouping worksheet.