How to Subtract Fractions

Subtracting Fractions

Fractions can be subtracted.

Imagine you wanted to subtract 1/5 (one-fifth) from 4/5 (four-fifths).

How to Subtract Fractions

It is easy to subtract fractions when the bottom numbers (called the denominators) are the same.

It is slightly trickier to subtract fractions when the bottom numbers are different.

A Real Example of How to Subtract Fractions with the Same Denominator

Question

Subtract the fractions below.

Step-by-Step:

1

Subtract the top numbers (caleed the numerators) of both fractions.

4 − 1 = 3

Place the answer above their common denominator.

2

Simplify the fraction if possible. (The fraction in our example is already as simple as possible).

Answer:

4/5 (four-fifths) minus 1/5 (one-fifth) equals 3/5 (three-fifths).

4/51/5 = 3/5

How to Subtract Fractions with Different Denominators

Question

Subtract the fractions below.

In this example, the bottom numbers (the denominators) are different. Before our fractions can be subtracted, we must make the denominators the same. In other words, we must find a common denominator for both fractions.

The common denominator can be found using one of the methods below:

The Common Denominator Method

The slider below shows how to subtract 2/5 from 2/3 using the common denominator method.

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The Least Common Denominator Method

The slider below shows how to subtract 2/5 from 2/3 using the least common denominator method.

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See Also

What is a fraction? What is a numerator? What is a denominator? Simplifying fractions What is a factor? What is a multiple? What is the least common multiple?