A free maths reference · est. 2026

Maths,
explained plainly.

130 lessons across 8 topics, each built the same way: the idea in plain words, a worked example you can follow line by line, the formulas worth remembering, and where it turns up in real life.

Browse all topics →Start at your level

8 topics

01NumbersFractions, decimals, percentages, primes, powers and the rules that hold them together.36 lessons
02Times TablesThe 1 to 12 times tables: patterns, tricks and checked practice, with a 12 by 12 chart.12 lessons
03AlgebraLetters for unknowns: expressions, equations, functions and the graphs that picture them.16 lessons
04GeometryShape and space: angles, triangles, circles, area and moving shapes around a plane.18 lessons
05Data & StatisticsCollecting, picturing and summarising data, and reasoning about chance.14 lessons
06MeasurementUnits, length, area, volume, time and moving confidently between measurement systems.16 lessons
07CalculusThe mathematics of change: limits, derivatives, integrals and the chain rule.4 lessons
08Money & FinanceInterest, compound growth and budgeting, the maths behind everyday money decisions.14 lessons

Start where you are

Not sure where to begin? Pick the stage that fits and we will point you at the right lessons and tools.

Ages 5–8

Beginners

Counting, comparing, shapes, simple measuring and telling the time.

Open the beginners guide →

Ages 9–12

Primary

Fractions, decimals, percentages, angles, area, averages and units.

Open the primary guide →

Ages 13–16

Secondary

Algebra, equations, quadratics, transformations, probability and interest.

Open the secondary guide →

Ages 17+

Advanced

Calculus, functions, standard deviation and compound growth.

Open the advanced guide →

Good places to start

Numbers

Fractions Explained

A fraction names part of a whole: the bottom number says how many equal parts, the top number says how many of them you have.

Algebra

Quadratic Equations

A quadratic has an x² term. Its graph is a parabola, and it can have two, one or no real solutions.

Geometry

Triangles

Three sides, three angles that always add to 180 degrees. Equilateral, isosceles and scalene triangles are named by their sides.

Data & Statistics

Introduction to Probability

Probability puts a number on uncertainty, from 0 for impossible to 1 for certain.

Calculus

Derivatives

The derivative measures instantaneous rate of change: the gradient of a curve at a single point.

Money & Finance

Compound Interest

With compound interest, each period earns interest on everything so far, including past interest. Growth snowballs.

From the dictionary

194 maths words, each defined in a sentence or two with an example.

Full A–Z →

Calculators that show their working

Check an answer, then see the method behind it.

All tools →