Number

Fractions, percentages, ratio, powers and more — the building blocks that everything else in maths sits on.

Integers, Powers and Roots

Whole numbers, squares, cubes, roots and the index laws that tie them together.
Fractions, Decimals and Percentages

Three ways of writing the same thing — and how to switch between them without breaking a sweat.
Percentage Change & Reverse Percentages

Increases, decreases, and the sneaky ones where you work backwards to the original amount.
Compound Interest & Depreciation

What happens when a percentage change stacks on top of itself, year after year.
Ratio and Proportion

Sharing amounts, scaling recipes, and keeping quantities in step with each other.
Bounds and Accuracy

Rounding, and working out the biggest and smallest a rounded number could really be.
Standard Form

A tidy way to write really big and really small numbers without a page full of zeros.
Surds

Roots that won't simplify to a neat number — and how to handle them exactly.