About Solid Number

Solid Number is a focused Number and Algebra study resource for Hong Kong Secondary 2–3 students learning in English.

We explain formulas through clear notes, worked examples and short drills. Each lesson highlights key formulae, a worked example, written practice and a multiple-choice review quiz.

Editorial approach

State the formula and when it applies.
Show a worked example in clear steps.
Use exam-style practice without unnecessary jargon.
Keep multipliers, signs and final checks visible.