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How to Subtract Fractions

Learn how to subtract fractions by finding common denominators, subtracting numerators, simplifying answers, avoiding mistakes, and troubleshooting.

EducationEdited by Pramod Tiwari
2 min read

Quick Answer

To subtract fractions, make the denominators the same, subtract the numerators, keep the common denominator, and simplify the result. If the denominators already match, subtract the top numbers directly.

What You Need

  • Fractions to subtract
  • Pencil and paper
  • Multiplication facts
  • Common denominator method
  • Simplifying method

Safety Precautions

  • Do not subtract denominators.
  • Use equivalent fractions when changing denominators.
  • Simplify the final answer when possible.
  • Handle mixed numbers carefully.
  • Check signs if subtracting negative fractions.

Step-by-Step Instructions

  1. Step 1

    Check denominators

    See whether the bottom numbers are already the same.

  2. Step 2

    Find a common denominator

    Use the least common denominator or another shared multiple.

  3. Step 3

    Rewrite fractions

    Multiply numerator and denominator by the same factor for each fraction.

  4. Step 4

    Subtract numerators

    Subtract the top numbers while keeping the denominator.

  5. Step 5

    Borrow if needed

    For mixed numbers, regroup if the first fraction part is smaller.

  6. Step 6

    Simplify

    Reduce the answer to simplest form.

  7. Step 7

    Check reasonableness

    Make sure the result makes sense compared with the starting fractions.

Practical Example

Example: To subtract 3/4 - 1/6, use denominator 12. Rewrite as 9/12 - 2/12 = 7/12.

Common Mistakes

  • Subtracting denominators
  • Forgetting to change numerators
  • Using different multipliers incorrectly
  • Not simplifying
  • Mishandling mixed numbers
  • Dropping negative signs

Troubleshooting

Denominators are different

Find a shared multiple and rewrite both fractions first.

Top fraction is smaller

Use mixed-number borrowing or convert to improper fractions.

Answer is not simplified

Find a common factor and reduce it.

Result seems too large

Check whether you accidentally added or changed denominators.

FAQs

Do you subtract denominators?

No. Once denominators match, subtract only the numerators.

What if denominators are different?

Rewrite both fractions with a common denominator before subtracting.

How do mixed numbers work?

You can borrow from the whole number or convert mixed numbers to improper fractions.

Should I simplify the answer?

Yes, unless your teacher or form asks otherwise.

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