Math explained

Long multiplication explained: the order that makes it stick

The order that makes long multiplication stick: the times-table check, 36 × 24 as an area model, the placeholder zero, and the four mistakes that ruin the second row.

Decimals explained for parents: reading, comparing and using them at home

Decimals break the one rule children trust about numbers: more digits means bigger. This guide explains decimal place value, the padding step that settles any comparison, and the money and kitchen examples that make it stick.

Mean, median and mode explained, with worked examples

Three summaries of the same list of numbers give three different answers, and all of them are correct. Here is how to find the mean, the median and the mode, with worked examples, the even-count rule and the mistakes that cost marks.

Prime numbers explained: how to spot them and why they matter

What makes a number prime, why 1 is left out, the square-root test that settles any number under 100, prime factorization with factor trees, and the six mistakes children make.

How to calculate percentages: three formulas and the mental shortcuts

Every percentage question is one of three calculations. Here are the three formulas with a worked example each, the 10% trick for doing them in your head, and the mistakes that make a sale price or a news headline come out wrong.

How to teach long division, with worked examples

The four steps of long division, three fully worked examples, the partial quotients method many schools teach first, and the mistakes that cost the most marks.

The order of operations, worked out step by step

One rule, several acronyms, and one detail almost everyone gets wrong. Five worked examples from a single multiplication up to nested brackets with an exponent, plus an honest answer to the viral equations.