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10 printable sets · answer key on every set

Adding and Subtracting Fractions Worksheets

  • CCSS 4.NF.B.3
  • 20 problems per set
  • Answer key included

What this skill is

Adding or subtracting fractions that already have the same bottom number: the bottom stays and only the tops change.

When it comes up: Fourth grade.

The mistake to watch for

Adding the bottom numbers too, so that 3/8 + 2/8 becomes 5/16. The pieces are eighths and they stay eighths.

How to help

Say the unit: three eighths plus two eighths is five eighths, just like three apples plus two apples is five apples.

Next: Adding fractions with different bottom numbers in fifth grade.

A worked example

3/8 + 2/8 = ___. The pieces are the same size (eighths), so add the tops and keep the bottom: 3 + 2 = 5, so 5/8. For subtraction, 7/8 − 4/8 = 3/8.

Words to know

fraction
A number that names equal parts of a whole, like 3/4.
numerator
The top number in a fraction. It tells how many parts we mean.
denominator
The bottom number in a fraction. It tells how many equal parts the whole is cut into.
add
To put numbers together to find how many in all.
subtract
To take one number away from another to find how many are left.

Practice

Add or subtract. The denominators are the same.

Showing Set 1 · 20 problems

  1. 1/12 + 2/12 = ___
  2. 4/5 − 3/5 = ___
  3. 6/9 − 3/9 = ___
  4. 1/4 + 1/4 = ___
  5. 3/10 − 1/10 = ___
  6. 5/9 − 4/9 = ___
  7. 6/9 − 4/9 = ___
  8. 3/9 − 2/9 = ___
  9. 6/7 − 3/7 = ___
  10. 6/12 − 3/12 = ___
  11. 5/6 − 3/6 = ___
  12. 4/7 − 3/7 = ___
  13. 3/7 + 3/7 = ___
  14. 3/6 − 2/6 = ___
  15. 3/4 − 2/4 = ___
  16. 7/10 − 5/10 = ___
  17. 5/8 − 1/8 = ___
  18. 9/12 − 6/12 = ___
  19. 9/10 − 3/10 = ___
  20. 5/9 − 3/9 = ___

Download this set20 problems · answer key included PDF

Answer key
  1. 3/12
  2. 1/5
  3. 3/9
  4. 2/4
  5. 2/10
  6. 1/9
  7. 2/9
  8. 1/9
  9. 3/7
  10. 3/12
  11. 2/6
  12. 1/7
  13. 6/7
  14. 1/6
  15. 1/4
  16. 2/10
  17. 4/8
  18. 3/12
  19. 6/10
  20. 2/9

All 10 sets

Each set is a different list of 20 problems with its own answer key. Use the buttons above to look at one on this page, or download any of them as a PDF.

How these sheets were made
  • Problems are generated for each set and checked against 4.NF.B.3 before the sheet is built — no duplicates, and every problem falls inside the standard's number range.

Common Core State Standards © 2010 National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.