Guide
How to Subtract Fractions with Different Denominators
Subtracting unlike fractions uses the same trick as adding them: match the denominators first, then subtract the tops.
Just like addition, you can only subtract fractions when their denominators match. Rewrite both over a common denominator, then subtract the numerators.
Step by step
- 1Find the least common denominator
Find the smallest number both denominators divide into. For 5/6 and 1/4, the LCD is 12. - 2Rewrite each fraction over the LCD
5/6 = 10/12 and 1/4 = 3/12. - 3Subtract the numerators
10/12 - 3/12 = 7/12. - 4Simplify
Reduce if possible. 7/12 is already in lowest terms.
Worked example
Subtract 5/6 - 1/4. The LCD of 6 and 4 is 12. Rewrite as 10/12 - 3/12. Subtract: 10 - 3 = 7. The answer is 7/12.
Common mistakes to avoid
- Subtracting denominators as well as numerators.
- Subtracting in the wrong order (order matters for subtraction).
- Leaving the answer unsimplified.
Practice this skill
Try it yourself on the Subtract Fractions Calculator, generate a printable worksheet, or work through it one step at a time in guided practice.
Frequently asked
How do you subtract fractions with unlike denominators?
Find a common denominator, rewrite both fractions over it, subtract the numerators, and simplify.
Does order matter when subtracting fractions?
Yes. 3/4 - 1/2 is not the same as 1/2 - 3/4, just as with whole numbers.
What if the answer is negative?
If the second fraction is larger, the result is negative — that's fine and the method is the same.