Fractions, Decimals and Percentages: One Idea, Three Costumes

A lot of KS3 students treat fractions, decimals and percentages as three separate topics. They’re not. They’re three ways of writing the same proportion.

The big idea

\frac{1}{2} = 0.5 = 50\%

All three say "one half". Once you can move between the three costumes, questions that look hard often become easy.

Quick conversions

Fraction → decimal: divide the top by the bottom.
Decimal → percentage: multiply by $100$ .
Percentage → fraction: write it over $100$ and simplify.

Reference table worth memorising

Fraction	Decimal	Percentage
$\frac{1}{2}$	$0.5$	$50\%$
$\frac{1}{4}$	$0.25$	$25\%$
$\frac{1}{5}$	$0.2$	$20\%$
$\frac{1}{10}$	$0.1$	$10\%$

Memorise these four and you can build most others quickly. Ready to test yourself? Grab a free practice paper.

Fractions, Decimals and Percentages: One Idea, Three Costumes

The big idea

Quick conversions

Reference table worth memorising

Practise this topic

KS3 Fractions Test Paper with Mark Scheme

KS3 Percentages Test Paper with Mark Scheme

KS3 Decimals & Rounding Test Paper with Mark Scheme