Add & Subtract Fractions

Maths: Year 5 & 6 National Curriculum, topic 1.4.3

Adding and Subtracting Fractions With the Same Denominator

When we add or subtract fractions, we must make sure the denominator of both fractions is the same.

If the denominator of both fractions is already the same we simply add or subtract the numerators.

$What is $$\frac{4}{5} - \frac{1}{5}$$?$

The denominators are the same so we just need to subtract the numerators (4 − 1 = 3).
Keep the denominator the same.

When we add or subtract fractions, we must make sure the denominator of both fractions is the same.

If the denominators are NOT the same, we need to make them the same using an equivalent fraction.

When finding an equivalent fraction we must multiply or divide both the top and bottom row by the same amount.

Once both the fractions have the same denominator, we can add or subtract the numerators.

$What is $$\frac{3}{4} - \frac{1}{5}$$?$

We cannot do the subtraction straight away because the fractions do NOT have the same denominator.

$What is $$\frac{3}{4} - \frac{1}{5}$$?$

Using equivalent fractions, convert the fraction so that they have the same denominator.

$What is $$\frac{3}{4} - \frac{1}{5}$$?$

Once both the fractions have the same denominator, we can add or subtract the numerators.