Subtraction within 20 worksheets
Subtraction within 20 for grades 1 and 2: 30 facts that cross 10, like 13 − 8 and 15 − 7, then mixed facts and missing numbers such as 14 − ___ = 6.
Download the free subtraction within 20 worksheet (PDF)
Subtraction within 20 worksheet
What’s on the worksheet
- 50 questions on subtraction within 20, sized for US Letter paper
- 2 pages of questions plus an answer key on the last page
- Written for grades 1–2, matching Common Core 1.OA.C.6, 2.OA.B.2
- Name and date lines at the top, and room to show the work
Sample questions from this worksheet
- 12 − 5 =
- 15 − 6 =
- 11 − 2 =
- 18 − 9 =
- 11 − 3 =
- 17 − 3 =
Preview the worksheet and answer key
Make a new subtraction within 20 worksheet
Need another page for extra practice, a retake or a second group in class? The free Mathify Kids test maker builds a fresh subtraction within 20 worksheet with different numbers every time. Choose how many questions, print it with its own answer key, or let your child take it on screen and see the score straight away.
Subtraction within 20: a worked example (13 − 8)
- Think addition: 8 + what makes 13?
- 8 + 2 = 10, and 3 more makes 13.
- 2 + 3 = 5, so 13 − 8 = 5.
What each part practices
- Part A (questions 1–30): Facts within 20, most of them crossing 10, like 13 − 8 and 16 − 9. These are the facts that need a strategy, not just counting back.
- Part B (31–50): A mix of plain facts and missing numbers in both places: 14 − ___ = 6 and ___ − 7 = 9. Every missing number can be found with an addition fact.
The answer key on the last page lists every answer in order, so a grown-up or an older child can mark the sheet in a couple of minutes.
How to use it at home and in class
At home
Practice the matching addition fact first: if your child knows 8 + 5 = 13, ask 13 − 5 and 13 − 8 straight away. Ten problems a day works better than a whole sheet at once. Mark them together with the answer key, then ask your child to explain one they got wrong: finding the mistake themselves is where the learning happens.
In class
Use the first row as a warm-up, a full page for independent practice, or five questions as an exit ticket. For a retake or a second group, make a new version with the test maker so every child gets different numbers.
Mistakes to watch for
- Counting back 8 on fingers, which is slow and often off by one.
- Taking the ones from each other: 8 − 3 = 5 is right here by luck, but 14 − 6 = 12 is not.
What to practice before and after subtraction within 20
- Before: fact families. If this sheet is a struggle, go back a step.
- After: subtraction facts, once this one is mostly right.
- Learn it first: the subtraction within 20 lesson and the subtraction chart.
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Questions parents ask
When should kids know subtraction facts within 20?
Grade 1 subtracts within 20 with strategies; by the end of grade 2, all facts within 20 should be quick, using mental strategies (2.OA.B.2).
What grade is this subtraction within 20 worksheet for?
It is written for grades 1–2 and matches Common Core standards 1.OA.C.6, 2.OA.B.2.
Can I get a different version of this subtraction within 20 worksheet?
Yes. Use the free Mathify Kids test maker to make a new subtraction within 20 worksheet with different numbers every time, with its own answer key.