Number 3

2 marks · Normal

Is 1 a prime number? Explain your answer.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

No, 1 is not a prime number because it only has one factor (itself).

Also accept: No; prime numbers have exactly two factors: 1 and itself. 1 only has one factor.; No; 1 is not prime because it only has one factor.

Common mistakes: Saying 1 is a prime; Incorrect definition

Show mark scheme and worked solution

Marking points

B1 · 1 mark · States correctly that 1 is NOT a prime number.

B2 · 1 mark · Mentions that a prime number has two factors or gives the correct reason.

Worked solution

No, 1 is not a prime number because it has only one factor (itself). Prime numbers have exactly two factors: 1 and the number itself.