Is 5 a prime number?
5 is a prime number. Here is how to check it, one division at a time.
The answer
Yes. 5 is a prime number: its only factors are 1 and 5.
How to check that 5 is prime
Try dividing 5 by the prime numbers, starting with 2. You only need primes: if 4 went into 5, then 2 would too.
- 5 ÷ 2 = 2 remainder 1, so 2 is not a factor.
Stop at 3: 3 × 3 = 9, which is more than 5. Any factor bigger than that would need a partner smaller than 3, and you have already tried those. So 5 is prime.
Where 5 comes among the primes
5 is the 3rd prime number. The prime just before it is 3.
There are 25 prime numbers up to 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97.
Around 5
- 5 is in only one times table, its own, as 5 × 1. The next answer in it is 5 × 2 = 10.
- The nearest square number is 4 (2 × 2), 1 below it.
5 at a glance
- In words
- five
- In Roman numerals
- V
- Odd or even
- Odd: it ends in 5
- Its factors add up to
- 6, or 1 without 5 itself, which makes 5 a deficient number
Related pages
More numbers
Questions parents ask
Is 5 one of a pair of twin primes?
Yes. Twin primes are two primes 2 apart, and 5 pairs with 3 and 7, so it is in two pairs.
What is the next prime number after 5?
7, which is 2 more than 5. Every number in between has a factor other than 1 and itself.
What is 5 × 5?
5 × 5 = 25. The square of a prime has exactly three factors: 1, 5 and 25.
Number facts are the base of 11+ maths
Factors, multiples, primes and square numbers come up all over 11+ maths, from simplifying fractions to ratio. The free diagnostic checks maths, English and both kinds of reasoning, and shows what to practise next. No card is required.