Subtraction Within 20

Grade 1MathCCSS 1.OA.C.6

Skill: Subtracting from numbers up to 20

10 versions for extra practice: this skill comes in 10 printable versions with the same layout and different problems, each with its own answer key. See all versions below, or download all 10 in one PDF (all answer keys).

Free for personal and classroom use. Print at 100% / "Actual size" on US Letter paper.

About this worksheet

After children learn to subtract within 10, the next step is subtraction within 20, including problems that cross ten, such as 15 - 7 or 13 - 8. This first-grade worksheet gives 24 vertical subtraction problems where the starting number is between 11 and 20 and the answer is never negative. Both the minuend and the subtrahend stay within the numbers first graders meet every day, so the focus stays on strategy rather than on huge numbers.

Crossing ten is the hard part for many children. The "make ten, then subtract the rest" idea helps: for 14 - 6, first subtract 4 to reach 10, then subtract the remaining 2 to get 8. Thinking of addition also works well. To solve 16 - 9, ask, "9 plus what makes 16?"

How to use it: let your child try a few problems with counters or a number line from 0 to 20. Then encourage a strategy that uses ten. Counting back one by one is fine while learning, but it becomes slow as numbers grow. When a problem is missed, model it with objects and rewrite it as a related addition fact.

The separate answer-key PDF lists every difference in order. This worksheet supports Common Core standard 1.OA.C.6 (add and subtract within 20, using strategies such as counting on, making ten, decomposing a number leading to a ten, and using the relationship between addition and subtraction). It pairs naturally with our Addition Within 20 worksheet.

All 10 versions

Each version practices the same skill with a fresh set of problems, so children can keep practicing without repeating a page they have already done. Problems are not repeated between versions unless a skill has only a small number of possible problems (for example, the addition facts within 10).