Fractions Calculator | Mometrix Academy

Use this calculator to help you quickly add, subtract, multiply, or divide fractions.

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Knowing how to add, subtract, multiply, and divide fractions is an important math concept to understand!

Take a look at these examples to see how each operation is performed:

Adding Fractions

Denominator is the Same

💡 Add \(\frac{3}{8} + \frac{7}{8}\).

Notice that both fractions have the same denominator, which is 8. This tells us we’re working with “eighths.”

Now, all we have to do is add the numerators together: \(3+7=10\).

\(\frac{3}{8} + \frac{7}{8} = \frac{10}{8}\)

Notice that our answer is an improper fraction, which means the numerator is larger than the denominator. Let’s simplify this.

To simplify, we can divide 10 by 8:

\(10 \div 8 = 1\frac{2}{8}\)

The fraction \(\frac{2}{8}\) can be simplified to \(\frac{1}{4}\), so our final answer is 1\(\frac{1}{4}\)!

Denominator is Different

💡 Add \(\frac{1}{4} + \frac{1}{2}\).

Notice that the fractions have different denominators, 4 and 2. This means we need to find a common denominator before we can add them.

The least common denominator (LCD) is the smallest number that both denominators divide into evenly. In this case, the LCD of 4 and 2 is 4.

We need to rewrite the fraction \(\frac{1}{2}\) so that it has a denominator of 4. To do this, we multiply both the numerator and denominator by 2:

\(\frac{1}{2} \times \frac{2}{2} = \frac{2}{4}\)

Now we can rewrite the original problem with the common denominator:

\(\frac{1}{4}+\frac{2}{4} =\) ?

Now that the denominators are the same, we can add the numerators: \(1 + 2 = 3\).

\(\frac{1}{4}+ \frac{2}{4} = \frac{3}{4}\)

Subtracting Fractions

Denominator is the Same

💡 Subtract \(\frac{7}{8} – \frac{3}{8}\).

Notice that both fractions have the same denominator, which is 8. This tells us we’re working with “eighths.”

Now, all we have to do is subtract the numerators: \(7-3=4\).

\(\frac{7}{8} – \frac{3}{8} = \frac{4}{8}\)

Both 4 and 8 are divisible by 4, so we can simplify our answer:

\(\frac{7}{8} – \frac{3}{8} = \frac{4}{8} = \frac{1}{2}\)

Denominator is Different

💡 Subtract \(\frac{1}{2} – \frac{1}{4}\).

Notice that the fractions have different denominators, 2 and 5. This means we need to find a common denominator before we can subtract them.

The least common denominator (LCD) is the smallest number that both denominators divide into evenly. In this case, the LCD of 2 and 4 is 4.

We need to rewrite the fraction \(\frac{1}{2}\) so that it has a denominator of 4. To do this, we multiply both the numerator and denominator by 2:

\(\frac{1}{2} \times \frac{2}{2} = \frac{2}{4}\)

Now we can rewrite the original problem with the common denominator:

\(\frac{2}{4}-\frac{1}{4} =\) ?

Now that the denominators are the same, we can subtract the numerators: \(2-1=1\).

\(\frac{2}{4}- \frac{1}{4}=\frac{1}{4}\)

Multiplying Fractions

💡 Multiply \(\frac{2}{3} \times \frac{4}{5}\).

To multiply fractions, you simply multiply the numerators together and the denominators together.

Multiply the numerators: \(2 \times 4=8\)
Multiply the denominators: \(3 \times 5=15\)

Put the new numerator on top of the new denominator, and you have the final answer!

\(\frac{2}{3} \times \frac{4}{5} = \frac{8}{15}\)

Dividing Fractions

💡 Divide \(\frac{2}{3}\) \(\div\) \(\frac{1}{4}\).

To divide fractions, you “invert and multiply.” This means you flip the second fraction (the divisor) and then multiply the fractions.

Invert the second fraction: \(\frac{1}{4}\) becomes \(\frac{4}{1}\)
Multiply the fractions: \(\frac{2}{3} \times \frac{4}{1} = \frac{8}{3}\)

Therefore, \(\frac{2}{3} \times \frac{1}{4} = \frac{8}{3}\)!

More Resources

Click below to watch a comprehensive video about adding, subtracting, multiplying, and dividing fractions, along with other helpful resources to help you fully grasp the topic!

Learn More About Fractions!