GlossariesGCSE GlossariesGCSE Maths GlossarySet notation

Set notation - GCSE Maths Definition

Reviewed by: Dan Finlay

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In GCSE Mathematics, set notation is used mainly in probability, to indicate we are referring to a combination of events. We are usually after one of three combinations of events

  • P(A and B) - the probability of events A and B occurring

  • P(A or B) - the probability of event A or event B occurring

  • P(not A) - the probability of event A not occurring

In set notation, these three would be written using the intersection symbol, intersection, the union symbol, union, and using a dash, ', (apostrophe, technically called prime) as follows

  • P(A intersection B) - the probability of events A and B occurring

  • P(A union B) - the probability of event A or event B occurring

  • P(A') - the probability of event A not occurring

Loosely speaking, we can remember intersection as meaning 'and', union as meaning 'or' and 'dash' as meaning 'not'. Set notation is often used alongside Venn diagrams.

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Dan Finlay

Reviewer: Dan Finlay

Expertise: Maths Subject Lead

Dan graduated from the University of Oxford with a First class degree in mathematics. As well as teaching maths for over 8 years, Dan has marked a range of exams for Edexcel, tutored students and taught A Level Accounting. Dan has a keen interest in statistics and probability and their real-life applications.

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