Using the Diameter Directly in Circumference Questions
You do not have to halve the diameter first unless you want to; C = πd is often the quickest formula.
Read this noteMaths help for the step you are stuck on
Clear maths. No mystery steps.
OnTrick Maths is a small collection of worked explanations for percentages, algebra and geometry. We show the working, point out where people usually slip up, and give you a quick way to check the answer.
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Three useful starting points
Pick the topic that matches your question. Each section mixes full guides with shorter notes, so you can go straight to the part you need.
01%
Percentages & ratios
Percentage change, reverse percentages, ratios, fractions and unit conversions.
Explore the topic → 02xAlgebra
Equations, fractions in algebra, simultaneous equations and completing the square.
Explore the topic → 03△Geometry
Area, perimeter, circles, sectors, trapeziums, volume and sensible unit checks.
Explore the topic →Worth learning properly
Three methods that save a lot of mistakes
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Short notes for common questions
Volume of a Prism: Area of Cross-Section × Length
Every prism volume follows the same idea: find the constant cross-section area, then multiply by the length.
Read this noteFinding the Mean from a Frequency Table
Multiply each value by its frequency, add the products, then divide by the total frequency.
Read this noteWhy Area Uses Square Units and Volume Uses Cubic Units
The powers in cm² and cm³ are not decoration. They tell you how many dimensions are being multiplied together.
Read this noteArea or Perimeter? A Simple Way to Tell What the Question Wants
If the question is about covering the inside, think area. If it is about the boundary or distance around, think perimeter.
Read this noteTurning a Recurring Decimal into a Fraction
A short algebra trick turns recurring decimals into exact fractions instead of rounded approximations.
Read this noteA simple rule for using this site
Read the working. Cover it up. Try the next one yourself.
That small pause is where the learning happens. If your answer looks odd, check the sign, the units and the original value before starting again.