What fraction of 1 metre is 25 cm?

1/4. 1 m = 100 cm, and 25/100 = 1/4.

Which is the biggest: 1/6, 1/2, 1/10 or 1/3?

1/2. Cutting into 2 gives the biggest pieces.

15. 1/4 of 20 = 5, so 3/4 = 3 × 5 = 15.

11+ Maths · Topic explained

What a fraction is

You get 1/4 of a pizza. I get 1/3. Who gets more?

The big idea

A fraction is part of a whole: the bottom number counts the equal parts, the top counts the parts you have.

Picture it

Cut a pizza into 4 equal slices and take 3: that's three quarters. Fewer slices means bigger slices.

Key words

numerator: The top number: how many parts you have.
denominator: The bottom number: how many equal parts the whole is cut into.
equal parts: Parts that are all exactly the same size.
unit fraction: One part of the whole: 1/2, 1/3, 1/4…

Worked examples

1Warm-up
A pizza is cut into 8 equal slices. 3 are eaten. What fraction is eaten?
- 8 equal slices: the denominator is 8
- 3 eaten: the numerator is 3
- 3/8 is eaten
211+ standard
Put in order, smallest first: 1/3, 1/8, 1/5
- Same top number: the bigger the bottom, the smaller the slices
- 1/8, 1/5, 1/3
311+ standard
What fraction of an hour is 15 minutes?
- An hour is 60 minutes: 15/60
- Divide top and bottom by 15
- 15 minutes = 1/4 of an hour
411+ standard
What is 2/5 of 30?
- 1/5 of 30 = 30 ÷ 5 = 6
- 2/5 = 2 × 6 = 12

The common mistake

The mistake

1/8 is bigger than 1/3, because 8 is bigger than 3.

Instead

1/8 is smaller: sharing between 8 makes smaller slices than sharing between 3.

Why: The denominator is how many pieces the whole is cut into: more pieces, smaller pieces.

Where it comes up in the 11+

'What fraction is shaded?', comparing fractions, and finding fractions of amounts.

The video

Video coming soon

We're making a short video that explains what a fraction is step by step. Until then, everything it covers is on this page.

Free printable