Fractions, decimals and percentsGrade 5
Subtracting fractions with unlike denominators worksheets
Each problem asks the student to subtract one fraction from another with different denominators, such as 3/4 − 5/12. The key shows the simplified difference. You can set the largest denominator, allow mixed numbers and choose how many problems print.
- Fresh problems every time
- Answer key on its own page
- Print or PDF, Letter or A4
- Free, no sign-up
On this page
The step that causes the trouble
Subtracting fractions with the same denominator is easy to learn: subtract the numerators and keep the denominator. Unlike denominators add a step before it. The pieces have to be the same size before they can be taken away, which means renaming at least one fraction. This is a core fifth-grade skill, and it is where many students first feel fractions are hard.
Before using this sheet, a student should be able to find a common multiple and write an equivalent fraction. If either is uncertain, work through ordering fractions first.
Settings
- Skill is on Subtract fractions, and Denominators is on Unlike (different) for this page. Switching Denominators to Like gives a gentler warm-up sheet, and A mix alternates the two.
- Largest denominator can be anything from 4 to 20. Denominators of 2, 3, 4, 5, 6 and 8 keep common denominators small. The default of 12 allows pairs such as 4 and 12 and also 5 and 8.
- Use mixed numbers is off by default, so every problem is two proper fractions. Turn it on and both numbers become mixed numbers, which adds a layer: the student must handle the whole parts, and may need to regroup.
- Number of problems is between 8 and 30, and the default of 20 prints three across.
The generator always puts the larger fraction first, so no problem has a negative answer. A rare problem may have two equal fractions, and its answer is 0.
Worked example: 3/4 − 5/12
- Find a common denominator. 4 divides into 12, so 12 works.
- Rename 3/4: multiply the top and bottom by 3 to get 9/12. 5/12 stays as it is.
- Subtract the numerators: 9 − 5 = 4. The result is 4/12.
- Simplify. Both 4 and 12 are divisible by 4, so 4/12 = 1/3.
The sheet's instruction line asks for a simplified answer, and the key always prints the result in lowest terms. Here that means 1/3, not 4/12. If the numbers do not share a factor, nothing more is needed. For example, 5/6 − 3/8 uses the common denominator 24, giving 20/24 − 9/24 = 11/24, which is already simplest.
When a mixed-number sheet gives an answer greater than 1, the key prints it as a mixed number.
Reading errors on the answer key
- Subtracting the denominators too. A student who writes 3/4 − 5/12 as (5 − 3) over (12 − 4) is treating the denominators as numbers to combine. Remind them that the denominator names the size of the piece, and that size must match before pieces are taken away.
- Renaming only one fraction when both need it. In 5/6 − 3/8, neither denominator divides the other, so both must be renamed.
- Correct difference, not simplified. The student has the right idea. Remind them the final step is checking for a common factor.
- Wrong numerator after renaming. Typically the top was not multiplied by the same number as the bottom. Ask "what did I multiply the denominator by?"
A practical routine
Ask students to estimate first. 3/4 is 0.75 and 5/12 is a bit under one half, so the answer should be about one third. If their finished answer lands near 1/3, they have a good sign. After this skill, practice multiplying fractions, which needs no common denominator at all.