5th Grade Math · Add and Subtract Fractions with Unlike Denominators
One denominator is a multiple Worksheets
Fresh practice, ready to print. Answer key included.
Problems such as 1/2 + 1/6 and 3/4 − 1/2, where one denominator divides the other.
Make it yours
Or start with a ready-made version.
How it works: a quick refresher
The rules this worksheet practices, then one problem worked from start to finish.
| Strategy | How it works |
|---|---|
| A multiple is the quicker case | 1/2 + 1/6: sixths already work. 1/2 = 3/6, so 3/6 + 1/6 = 4/6 = 2/3. |
| Otherwise build a common denominator | 1/3 + 1/4. Twelfths work for both: 4/12 + 3/12 = 7/12. |
| Subtract the same way | Rewrite, then subtract the numerators. 2/3 − 1/2 = 4/6 − 3/6 = 1/6. |
| Simplify at the end | 4/6 is 2/3. The common denominator is a step, not always the final denominator. |
| Mixed numbers | Add or subtract the fractions, then the whole numbers. Regroup when a fraction is too small to subtract, or when the fractions add to more than 1. |
Worked example
Find 1/3 + 1/4.
- 13 and 4 share no factor other than 1. A common denominator is 3 × 4 = 12.
- 21/3 = 4/12 and 1/4 = 3/12.
- 34/12 + 3/12 = 7/12.
- 47 and 12 have no common factor, so 1/3 + 1/4 = 7/12.
Ready-made versions
Three fixed versions you can link to or share. Each is a PDF with its own answer key.
- One denominator is a multiple Worksheets, version 1Worksheet PDFAnswer key PDF
- One denominator is a multiple Worksheets, version 2Worksheet PDFAnswer key PDF
- One denominator is a multiple Worksheets, version 3Worksheet PDFAnswer key PDF
Grade level and standard
Written for 5th grade math (fractions) and aligned to CCSS 5.NF.A.1. It also works as review in later grades.
Common questions
- Is there an answer key?
- Yes. Every worksheet has a matching answer key with each answer worked on the same grid or layout as the question. The worksheet code printed at the bottom of each page pairs a sheet with its key.
- Does the common denominator have to be the least one?
- No. 24 also works for thirds and fourths: 8/24 + 6/24 = 14/24, which simplifies to 7/12. The least one is less to multiply, and the answer is the same.
- Why is 1/2 + 1/4 not 2/6?
- Adding the denominators does not name the new pieces. Halves and fourths are different sizes. Turn the half into fourths first: 2/4 + 1/4 = 3/4.
- How many different versions are there?
- About a million per skill. Each time you press the button the problems are generated fresh, so you can print a different version for every student, a retake, or another night of practice.
- Are the worksheets free?
- Yes. They are free to print and copy for your home or classroom, with no sign-up.
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