Prime numbers & factorisation
Edexcel GCSE Maths revision on Prime numbers & factorisation. Aligned to the Pearson Edexcel GCSE Mathematics 1MA1 specification. This bank has 16 practice questions on this topic.
Sample questions (3 of 16)
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Question 1
Which of these numbers is defined as a prime number?
- A) The integer 13 because it has two factors
- B) The integer 15 because it has three factors
- C) The integer 21 because it has four factors
- D) The integer 27 because it has four factors
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Answer: The integer 13 because it has two factors
The correct answer is 13 because a prime number has exactly two factors: 1 and itself. The numbers 15, 21, and 27 are composite as they have more than two factors.
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Question 2
What is the prime factorisation of the number 20 expressed in index notation?
- A) 2 squared times 5 is the correct prime expression
- B) 2 times 5 squared is the correct prime expression
- C) 4 squared times 5 is the correct prime expression
- D) 2 times 5 times 2 is the correct prime expression
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Answer: 2 squared times 5 is the correct prime expression
The prime factors of 20 are 2, 2, and 5. In index notation, this is written as 2^2 × 5, or 2 squared times 5. Choosing 4 squared times 5 is incorrect because 4 is not a prime number.
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Question 3
What is the product of the first three prime numbers?
Show answer
Answer: 30
The first three prime numbers are 2, 3, and 5. Multiplying these together (2 × 3 × 5) gives a product of 30.
Want to test yourself on the remaining cards for this topic?
13 more questions on Prime numbers & factorisation — plus mistakes tracking and spaced repetition across the whole Maths spec.