Learn | Grasp Maths

Lesson overview

Number - fractions

When fractions have the same denominator, the whole is split into the same size parts. We keep the denominator the same and combine or remove the numerators.

Add quarters

$\frac{1}{4} + \frac{2}{4} = \frac{3}{4}.$

The denominator stays as 4 because the parts are still quarters.

Subtract fifths

$\frac{4}{5} - \frac{1}{5} = \frac{3}{5}.$

Subtract the numerators and keep the denominator the same.

Use a fraction strip

Equal parts make the fraction calculation clear.

Three quarters.

The strip shows how many equal parts are counted.

Worked example

Work out $\frac{2}{8}$ + $\frac{3}{8}$ .

Check that both fractions have the same denominator.
They are both eighths, so the parts are the same size.
Add the numerators: 2 + 3 = 5.
So the answer is $\frac{5}{8}$ .

Try it

Check that the denominators match, then add or subtract the numerators.

Question 1

What is $\frac{1}{4}$ + $\frac{1}{4}$ ?

Question 2

What is $\frac{5}{6}$ - $\frac{2}{6}$ ?

Question 3

Write the numerator in $\frac{3}{8}$ + $\frac{2}{8}$ = $\frac{5}{8}$ .

Question 4

Which answer is correct for $\frac{4}{5}$ - $\frac{1}{5}$ ?

Question 5

What stays the same when we add fractions with the same denominator?

Common mistakes

Watch for these when working through the lesson.

Changing the denominator when the parts stay the same size.
Adding the denominator as well as the numerator.
Trying to go beyond one whole when the lesson stays within one whole.

Add and subtract fractions with the same denominator within one whole

Lesson overview

Worked example

Try it

Common mistakes

Related topics

Independent practice will plug in here