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Subtraction within 20

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Subtraction Within 20

  1. 1.9-6=
  2. 2.12-4=
  3. 3.17-12=
  4. 4.19-10=
  5. 5.8-2=
  6. 6.16-2=
  7. 7.19-5=
  8. 8.19-13=
  9. 9.15-14=
  10. 10.9-1=
  11. 11.11-4=
  12. 12.14-6=
  13. 13.17-13=
  14. 14.13-5=
  15. 15.12-0=
  16. 16.16-6=
  17. 17.12-11=
  18. 18.18-14=
  19. 19.9-2=
  20. 20.19-8=

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Subtraction Within 20, Answer Key

  1. 1.9-6=3
  2. 2.12-4=8
  3. 3.17-12=5
  4. 4.19-10=9
  5. 5.8-2=6
  6. 6.16-2=14
  7. 7.19-5=14
  8. 8.19-13=6
  9. 9.15-14=1
  10. 10.9-1=8
  11. 11.11-4=7
  12. 12.14-6=8
  13. 13.17-13=4
  14. 14.13-5=8
  15. 15.12-0=12
  16. 16.16-6=10
  17. 17.12-11=1
  18. 18.18-14=4
  19. 19.9-2=7
  20. 20.19-8=11

Created for free at puzzleandprint.com

Or take one that is already made

Four sheets in three lengths, 20, 50 and 100 problems. Every one is a two-page PDF, the worksheet, then the answer key on its own page.

Subtraction within 20 math worksheet printable, warm up: 20 problemsSubtraction within 20 math worksheet, warm up20 problemsDownload PDF ↓Subtraction within 20 math worksheet printable, everyday: 50 problemsSubtraction within 20 math worksheet, everyday50 problemsDownload PDF ↓Subtraction within 20 math worksheet printable, timed test: 100 problemsSubtraction within 20 math worksheet, timed test100 problemsDownload PDF ↓Subtraction within 20 math worksheet printable, second set: 50 problemsSubtraction within 20 math worksheet, second set50 problemsDownload PDF ↓

Every sheet here is free to print as often as you like. If one saved you time, the tip jar is on Ko-fi.

Subtraction lags addition for most children by a good few months, and the usual reason is that it is being counted backwards rather than recalled. Practice is what closes that gap, but only once the idea itself has landed. A page of subtraction will not teach a child what subtraction means.

Every problem on these sheets is ordered so the larger number comes first, which means the answer is never below zero. That is deliberate: negative numbers are a later topic, and meeting one by accident on a practice sheet is confusing rather than instructive.

The sheets run from twenty problems to a hundred. Fifty is the everyday size. Borrowing across ten (15 − 8 and its neighbors) is where most children slow down, so it is worth watching which ones cause the pause.

The generator will take any range you set if you want to narrow it, and the answer key prints separately so you can hand out the sheet without it.

Which subtraction within 20 facts cross ten, and how many are on each sheet

Thirty-six of the 231 possible problems on the subtraction within 20 sheets cross ten: a number from 11 to 18 with a single digit taken away, leaving an answer below ten, as in 15 − 8 = 7 or 13 − 6 = 7. They are the reverse of the 36 single-digit additions that cross ten, so 8 + 7 = 15 and 15 − 7 = 8 are one fact read in two directions, and practicing them together halves the work. The printed sheets carry 5 of them on the warm up, 8 on the everyday sheet, 16 on the timed test and 7 on the second set, and they are the problems to watch for counting on fingers.

The rest of the 231 fall into easier families. Taking a single digit from a number in the same ten, such as 19 − 6 = 13 or 16 − 2 = 14, needs only the ones digit. Taking away 10, or a number close to the starting number, such as 16 − 10 = 6 or 19 − 17 = 2, is quicker counted up from the smaller number than counted back from the larger, and choosing which way to go is part of the skill. Twenty is a starting number too, as in 20 − 6 = 14, which drops back below twenty in the same way that 15 − 8 drops below ten.

Why the subtraction within 20 sheets include 6 − 6 and 3 − 0

The subtraction within 20 sheets include problems like 6 − 6 and 3 − 0 because zero belongs to the range at both ends: a number can be taken from itself, leaving nothing, and nothing can be taken from a number. Of the 231 possible problems, 21 have an answer of zero, from 0 − 0 to 20 − 20, and 21 take away zero, from 0 − 0 to 20 − 0, which makes 41 problems in all once 0 − 0 is counted once. The everyday sheet has three answers of zero and five subtractions of zero. Each takes a second, and a child who hesitates on 3 − 0 is showing you something worth knowing.

All four subtraction sheets draw on the same 231 problems, so they step up in quantity rather than difficulty: 20 on the warm up, 50 on the everyday sheet, 100 on the timed test and another 50 on the second set. The timed test draws 100 different problems from the 231, close to half of everything subtraction within 20 contains. The second set shares 10 of its 50 problems with the everyday sheet, so it works as a fresh attempt rather than a repeat, and the New problems button in the maker draws another set from the same 231 whenever a further sheet is needed.

Common questions

Will any of these give a negative answer?

No. Each problem is built from two numbers between 0 and 20 with the larger one always placed first, so the lowest answer any sheet can show is zero, and the maker keeps that ordering for any range you set. Zero itself does turn up: once on the warm up, three times on the everyday sheet and the second set, and six times on the timed test.

My child is much slower at subtraction than addition. Is that normal?

Yes, and the gap usually sits in a small group of problems rather than across the whole sheet. On the timed test, 16 of the 100 problems cross ten, such as 13 − 8 and 16 − 9; if those are slow while 18 − 5 and 20 − 10 come quickly, asking what goes with 8 to make 13 lets the child use an addition fact already known.

What is the largest number on the subtraction within 20 sheets?

Twenty. The starting number in every problem is at most 20, and because the larger number always goes first, the biggest possible answer is 20 − 0 = 20.

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