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Geometry & MeasuresIntroduction

The Most Famous Number in Maths

Part of Circumference & Area of Circles · GCSE GCSE Mathematics revision

This introduction covers The Most Famous Number in Maths within Circumference & Area of Circles for GCSE Mathematics. Revise Circumference & Area of Circles in Geometry & Measures for GCSE Mathematics with 11 exam-style questions and 7 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 1 of 10 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 1 of 10

Practice

11 questions

Recall

7 flashcards

The Most Famous Number in Maths

For thousands of years, mathematicians noticed something magical: if you divide ANY circle's circumference by its diameter, you ALWAYS get the same number - π (pi) = 3.14159... This single number unlocks both the distance around a circle AND the space inside it!
Circle formulas showing parts of a circle (radius, diameter, circumference), pi explanation, formulas C=πd and A=πr², with worked examples for both circumference and area

Keep building this topic

Read this section alongside the surrounding pages in Circumference & Area of Circles. That gives you the full topic sequence instead of a single isolated revision point.

Key VocabularyThe Two Essential FormulasMethod: Finding Circumference

Practice Questions for Circumference & Area of Circles

A circle has radius r. Which pair of formulas gives the correct circumference C and area A?

  • A. C = πr², A = 2πr
  • B. C = 2πr, A = πr²
  • C. C = πd², A = πr
  • D. C = 2πr², A = πr
1 markfoundation

Explain why the circumference of a circle is measured in cm (or other length units) but the area is measured in cm² (square units).

2 markshigher

Quick Recall Flashcards

Circumference
C = πd or C = 2πr
Area of Circle
A = πr²

11 questions on Circumference & Area of Circles — practise free

Instant marking, adaptive difficulty, and 7 spaced repetition flashcards. Free until your GCSEs.

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