Imagine you wanted to add 1/5 (one-fifth) and 3/5 (three-fifths). It is easy to add fractions when the bottom numbers (called the denominators) are the same.

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

## A Real Example of How to Add Fractions with the Same Denominator

### Question # 1

Add the top numbers (called the numerators) of both fractions.

1 + 3 = 4

Place the answer above their common denominator. # 2

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

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

1/5 + 3/5 = 4/5

## How to Add Fractions with Different Denominators

### Question In this example, the bottom numbers (the denominators) are different. Before our fractions can be added, 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 add ½ and ⅓ using the common denominator method.

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## The Least Common Denominator Method

The slider below shows how to add ½ and ⅓ using the least common denominator method.

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