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Addition within 20

The first and second grade fluency goal, with answer keys.

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Addition Within 20

  1. 1.9+0=
  2. 2.4+5=
  3. 3.2+7=
  4. 4.3+6=
  5. 5.1+8=
  6. 6.10+7=
  7. 7.1+6=
  8. 8.10+6=
  9. 9.7+1=
  10. 10.5+9=
  11. 11.9+4=
  12. 12.4+6=
  13. 13.2+10=
  14. 14.9+1=
  15. 15.3+7=
  16. 16.2+1=
  17. 17.5+8=
  18. 18.6+6=
  19. 19.8+0=
  20. 20.9+10=

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Addition Within 20, Answer Key

  1. 1.9+0=9
  2. 2.4+5=9
  3. 3.2+7=9
  4. 4.3+6=9
  5. 5.1+8=9
  6. 6.10+7=17
  7. 7.1+6=7
  8. 8.10+6=16
  9. 9.7+1=8
  10. 10.5+9=14
  11. 11.9+4=13
  12. 12.4+6=10
  13. 13.2+10=12
  14. 14.9+1=10
  15. 15.3+7=10
  16. 16.2+1=3
  17. 17.5+8=13
  18. 18.6+6=12
  19. 19.8+0=8
  20. 20.9+10=19

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.

Addition within 20 math worksheet printable, warm up: 20 problemsAddition within 20 math worksheet, warm up20 problemsDownload PDF ↓Addition within 20 math worksheet printable, everyday: 50 problemsAddition within 20 math worksheet, everyday50 problemsDownload PDF ↓Addition within 20 math worksheet printable, timed test: 100 problemsAddition within 20 math worksheet, timed test100 problemsDownload PDF ↓Addition within 20 math worksheet printable, second set: 50 problemsAddition 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.

In the Common Core standards, first graders learn to add within 20 and second graders are expected to know those sums from memory, and it is the point at which arithmetic starts becoming automatic rather than counted out. Crossing ten is the hard part (a child who is confident to ten often stalls at 8 + 5), so a sheet that spans the whole range is more useful than one that stops at ten.

The four ready-made sheets step from a twenty-problem warm-up to a hundred-problem timed page, all drawn from the same 121 sums of two numbers from 0 to 10. Fifty is the everyday size, and at that length a sheet covers more than a third of the possible sums without repeating one.

Short and frequent beats long and occasional here. Five minutes a day does more for recall than forty minutes once a week, because what you are building is retrieval speed rather than understanding.

If your child or class needs a different range, the generator takes any range you set: 0 to 9 on both sides keeps to single digits, and 0 to 5 on both sides keeps every total at ten or less. Whatever the range, the answer key always prints on its own page.

How high do the totals go on the addition within 20 sheets

On the addition within 20 sheets both numbers run from 0 to 10, so no total can go above 20 and the largest sum, 10 + 10 = 20, is on all four sheets. Counting both orders, that range makes 121 different problems, and 36 of them pair two single digits that cross ten, such as 8 + 5 and 9 + 7. Those are the facts children are most likely to count out, and the printed sheets carry 6 of them on the warm up, 18 on the everyday sheet, 31 on the timed test and 20 on the second set, between 30 and 40 percent of each page.

Of the 121 problems, the 85 that do not cross ten fall into two easier groups. Twenty-one put a 10 on the page, such as 10 + 6 = 16 and 9 + 10 = 19, where adding ten leaves the ones digit of the other number unchanged. The remaining 64 are single-digit pairs whose total is ten or less, including the 9 that make exactly ten, such as 2 + 8 and 9 + 1, which are the bonds a child uses to cross ten by way of ten. On the everyday sheet 11 of the 50 problems contain a 10 and 21 are single-digit pairs totaling ten or less.

Is the second set of addition within 20 problems different from the everyday sheet

The second set of addition within 20 problems is mostly a different fifty: 29 of its 50 problems are not on the everyday sheet, and none of the 21 it shares sits in the same position, so it works as a retest a few days later without children remembering answers from the first attempt. No problem repeats inside a sheet either, since each is drawn from the 121 without replacement. Because 7 + 8 and 8 + 7 count as two problems, both orders can land on the same page, as they do on the everyday sheet and the second set, which is a good moment to point out that the second is free once the first is known.

The timed test comes closest to covering the whole range: it uses 100 of the 121 possible problems, and the 21 it leaves out include 1 + 1, 2 + 2 and 3 + 3, so a child who finishes it has met more than four in five of them. It sets them in five columns of 20, against four columns of 13 on the fifty-problem sheets and three columns of seven on the warm up. Sums with a zero appear on every sheet, 16 of them on the timed test alone, such as 8 + 0. They take a second each and are worth leaving in, because adding zero is a rule to know rather than something to count.

Common questions

Why within 20 rather than within 10?

Because crossing ten is the hard part, and a sheet whose totals stop at ten never asks for it. Of the 121 problems these sheets draw on, 36 are single-digit pairs that cross ten, such as 8 + 5 and 6 + 7, and a within-ten sheet contains none of them.

Which of the sheet sizes should I print?

Print the fifty-problem everyday sheet for regular practice and use the other three for particular jobs. The twenty-problem warm up opens a lesson, and its six crossing-ten sums, such as 8 + 7 and 9 + 5, show quickly whether those facts are recalled or counted. The second set has 29 problems the everyday sheet does not, for a retest, and the hundred-problem timed test suits a child who is already accurate and working on speed.

How do I make an addition sheet where no total goes over 20?

Every ready-made sheet on this page already keeps each total to 20 or less, because both numbers run from 0 to 10, and the maker opens with the same range. That range holds 121 possible problems, including the 11 pairs that make ten and the 36 single-digit pairs that cross ten, and the largest is 10 + 10 = 20. Lower either top number in the maker for smaller totals still.

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