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MA04-03 Maths Watch

Finding a common denominator

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Next: MA04-04 Adding and subtracting fractions and mixed numbers

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In this lesson

In this video you'll learn about finding a common denominator for GCSE Maths, with worked examples and the mistakes examiners report. By the end you'll be able to find a common denominator for two or more fractions by using the LCM of the denominators, rather than an unnecessarily large denominator.

What it covers

1:06 Finding a common denominator: the idea + baby-step question
3:12 The method, worked example 1
5:25 The trap + ExamCraft
7:42 Your turn, worked example 2
9:53 What's next

Key words

common denominator lowest common denominator lcm

For: Edexcel IGCSE 4MA1

On the specification

Board	Spec	Statement
Edexcel IGCSE 4MA1	F1.2C	Identify common denominators

For teachers

This GCSE Maths lesson teaches finding a common denominator. By the end, students should be able to find a common denominator for two or more fractions by using the LCM of the denominators, rather than an unnecessarily large denominator. It works through two worked examples and the mistakes examiners report.