Math Drill Pages

Addition Within 20 Worksheet

Every sum on this sheet is between 11 and 20, so each problem crosses ten. These are the facts first and second graders find hardest. The sheet has 30 problems and takes about 10 minutes.

Grade
Grade 1–2
Problems
30
Time
About 10 minutes
Standard
1.OA.C.6, 2.OA.B.2
Download PDF (US Letter) Download PDF (A4)

Two pages: the worksheet, then the answer key. No sign-up needed.

Worksheet preview

Part A Add.

  1. 1 + 10 = 11
  2. 7 + 7 = 14
  3. 10 + 3 = 13
  4. 4 + 10 = 14
  5. 5 + 9 = 14
  6. 2 + 9 = 11
  7. 8 + 8 = 16
  8. 3 + 8 = 11
  9. 6 + 7 = 13
  10. 3 + 10 = 13
  11. 4 + 9 = 13
  12. 7 + 10 = 17
  13. 9 + 9 = 18
  14. 9 + 4 = 13
  15. 6 + 9 = 15

Part B Add. Try to beat your Part A time.

  1. 9 + 3 = 12
  2. 9 + 5 = 14
  3. 10 + 4 = 14
  4. 9 + 2 = 11
  5. 7 + 4 = 11
  6. 6 + 6 = 12
  7. 7 + 5 = 12
  8. 10 + 9 = 19
  9. 10 + 2 = 12
  10. 8 + 4 = 12
  11. 8 + 9 = 17
  12. 6 + 10 = 16
  13. 4 + 8 = 12
  14. 8 + 10 = 18
  15. 6 + 8 = 14

Tips for teachers and parents

  • Teach "make a ten." For 8 + 5, move 2 from the 5 to the 8 to make 10, then add the 3 that is left: 13.
  • Use doubles as anchors. 7 + 8 is one more than 7 + 7 = 14, so it is 15.
  • Adding 10 is a quick pattern: 10 + 6 is 16. Use these as warm-ups if a student is stuck.
  • Time Part A and Part B separately and keep the scores. Speed should rise over a few weeks as counting turns into recall.

Common mistakes

  • Answers one too small or too large, such as 9 + 6 = 14, which come from counting on with the fingers. Practice make-a-ten with a ten frame.
  • Writing 11 to 19 in the wrong order, such as 51 for 15. Say the number in tens and ones: "one ten and five ones."

What to practice next

When the facts are quick, move on to 2-digit addition without regrouping.

Frequently asked questions

What is the make-a-ten strategy?

Split one number to fill the other up to 10, then add the rest. 9 + 4 becomes 10 + 3, which is 13.

When should children know addition facts to 20?

First graders add within 20 using strategies, and second graders are expected to know these facts from memory by the end of the year.

Why are there no sums below 11?

Sums of 10 or less are on the addition within 10 sheet. This sheet focuses on the facts that cross ten.