What is a prime number?

Definition

A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself.

Example

7 is prime because only 1 and 7 divide it exactly. 8 is not prime because 2 and 4 also divide it.

Tip

1 is not prime, and 2 is the only even prime.

Practise it

• Play: Prime Hunter
• Worksheets: Factors and multiples (Grade 4)
• Online maths practice

Quick check: try these

Work each one out on paper, then tap the question to see the answer.

1. How many factors does 8 have?

   Answer: 4

2. How many factors does 36 have?

   Answer: 9

3. How many factors does 30 have?

   Answer: 8

4. How many factors does 16 have?

   Answer: 5

Learn it in depth

Prime number is part of HCF and LCM for Class 6: notes, formulas, solved examples with every step, common mistakes and ten practice questions with answers. Want a teacher to go through it with you? See Class 6 maths tuition.

Related words

Factor, Multiple, Composite number