Missing Addends Within 1,000 Worksheets for 3rd Grade

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Grade 3MathAddition & SubtractionCCSS 3.NBT.A.2

Skill: Finding the missing addend in addition equations with sums up to 1,000

Preview of the Missing Addends Within 1,000 printable worksheet
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Teaching tips and what to try next

Aimed at third graders who add and subtract three-digit numbers with regrouping. Sketching an open number line and jumping from the known part to the total is often faster than column subtraction for these. For simpler numbers, step back to Missing Addends Within 100; for mixed column work, use Mixed 3-Digit Addition and Subtraction.

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

Third graders learn to add and subtract within 1,000 with confidence. A missing addend equation, such as 348 + ___ = 725, joins the two skills together: children can count up from the part they know, or subtract it from the total. This third-grade worksheet gives twenty equations like that, with totals from 200 to 1,000.

In every equation, both parts are at least 100, so each problem needs real work with hundreds, tens and ones. The missing part is sometimes the first number and sometimes the second. Many problems need regrouping when they are solved by subtraction, and some cross a hundred when they are solved by counting up. The equations are written across the page, so children may want to rewrite a problem in columns on scrap paper. Each of the ten versions has new equations and its own answer key.

How to use it: talk about the two ways to solve the first problem. One way is to subtract the known part from the total. Another is to count up from the known part to the next hundred, then on to the total, and add the jumps. Encourage your child to estimate first: if the total is about 700 and one part is about 300, the missing part should be about 400. Checking by adding the two parts back together catches most mistakes.

The answer key shows every missing addend. For smaller numbers, try our Missing Addends Within 100 worksheet. For column practice, try our Three-Digit Subtraction With Regrouping worksheet.