Adding Three Numbers

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Grade 1MathAddition & SubtractionCCSS 1.OA.A.2CCSS 1.OA.B.3

Skill: Adding three one-digit numbers with sums up to 20

Preview of the Adding Three Numbers printable worksheet
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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

Adding three numbers is a first-grade skill that builds number sense and mental math. When children see 4 + 6 + 3, they learn that they can add any two numbers first. Spotting the 4 and 6 that make ten turns the problem into an easy 10 + 3. This first-grade worksheet gives twenty problems, each with three numbers from 1 to 9 and a total of 20 or less.

Each problem is written across in one line, such as 7 + 2 + 3 = ___. Some problems have two numbers that make ten, and some have doubles like 5 + 5 or 4 + 4, so children can practice choosing a smart order. The ten versions never repeat a problem.

How to use it: before your child starts, solve one problem two ways. Add from left to right, then add the two numbers that make ten first, and show that both ways give the same total. Invite your child to circle the two numbers they will add first in each problem. Counters, cubes, or fingers are fine for checking an answer. If your child gets stuck, add the first two numbers, write that total above them, and then add the third number.

The answer key shows every full number sentence. This worksheet supports Common Core standards 1.OA.A.2 (solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20) and 1.OA.B.3 (apply properties of operations as strategies to add). Warm up with our Addition Within 20 worksheet, or practice making ten with our Number Bonds to 10 worksheet.