Addition and Subtraction Within 20 Worksheets for 1st Grade

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Grade 1MathAddition & SubtractionCCSS 1.OA.C.6

Skill: Adding and subtracting within 20 with mixed facts on one page

Preview of the Addition and Subtraction Within 20 printable worksheet
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Teaching tips and what to try next

Suited to first graders who know most single facts from Addition Within 20 and Subtraction Within 20. Speed comes from strategies, so ask which facts felt slow and practice only those on index cards for a few days. Linking each take-away fact to an addition partner is the next step, and Fact Families Within 20 builds that habit.

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).

Download all 10 versions (one PDF)All 10 answer keys (PDF)

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About this worksheet

Once first graders have practiced addition facts and subtraction facts on their own, the next step is a page that mixes them. Children have to look at the sign before they solve each problem, which is a habit many children skip when every problem on a page is the same kind. First graders are expected to add and subtract within 20, and this first-grade worksheet gives that mixed practice.

The page has thirty facts in three columns. Fifteen are addition facts that add two numbers from 1 to 10, such as 7 + 8. The other fifteen are subtraction facts that start with a number from 11 to 20 and take away a number from 1 to 10, such as 15 – 9. Addition and subtraction are mixed together in random order. Each of the ten versions has new facts and its own answer key, and across all ten versions every one of the 200 possible facts appears before any repeats.

How to use it: before your child starts, ask them to circle every minus sign on the page. That one step cuts down on careless mistakes. For subtraction, encourage your child to think addition: for 15 – 9, ask what goes with 9 to make 15. Making ten also helps, such as 8 + 5 is 8 + 2 + 3 = 13. Time is not important at first. Aim for accuracy, then try the same version a few days later.

The answer key gives every answer. For one operation at a time, try our Addition Within 20 worksheet and our Subtraction Within 20 worksheet. To connect the two, try our Fact Families Within 20 worksheet.