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Worksheets›Grade 1›Addition & subtraction›Addition within 20

Addition Within 20 Worksheets

Free printable worksheets with answer keys. Pick a level, preview the questions, then open the sheet to swap or delete any single question.

Grade 1CCSS 1.OA.C.6Answer key includedPDF · Print
Open in generatorStart with an easy sheet

Easy: Sums up to 10

  1. 1.7 + 1 =
  2. 2.5 + 4 =
  3. 3.8 + 0 =
  4. 4.0 + 10 =
  5. 5.5 + 3 =
  6. 6.9 + 0 =
Preview shows 6 of 12 questions. Every sheet is new; open it to change any question.

Worksheet variations

Students build fluency with addition facts. For sums past 10, the make-ten strategy breaks one addend apart: 8 + 5 = 8 + 2 + 3 = 13.

Easy4 + 6 =Sums up to 10Medium6 + 8 =Sums from 11 to 20Hard5 + 7 + 5 =Three numbers, sums up to 20

How to solve it: a worked example

Add.

  1. Start1 + 1 =
  2. Count on 1 from 11 + 1 = 2
  3. Answer2

Common mistakes to watch for

  • Counting the first number again when counting on, so 8 + 3 becomes 10.
  • Losing track of the leftover after making ten.
  • Adding only two of three numbers.

Tip: tick “Step-by-step answer key” in the generator to print each step for marking.

Related worksheets

Subtraction within 20Missing numbers in equationsTwo-digit addition (Grade 2)Two-digit subtraction (Grade 2)Adding & subtracting within 1000 (Grade 2)

FAQ

Is every worksheet different?

Yes. Numbers are generated each time, and the answer key is calculated for that sheet. Swap any single question and its answer updates too.

Can I mix addition within 20 with other skills?

Yes. In the generator, add more skills; each gets its own section on the sheet with its own instructions.

Is it free to print?

Yes. Generating and printing from the browser is free with no sign-up. PDF downloads need a free account.