Is 3 a prime number?
3 is a prime number. Here is how to check it, one division at a time.
The answer
Yes. 3 is a prime number: its only factors are 1 and 3.
How to check that 3 is prime
The only whole number between 1 and 3 is 2, and 3 ÷ 2 = 1 remainder 1. Nothing else goes into 3 exactly, so it is prime.
Where 3 comes among the primes
3 is the 2nd prime number. The prime just before it is 2.
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 3
- 3 is in only one times table, its own, as 3 × 1. The next answer in it is 3 × 2 = 6.
- The nearest square number is 4 (2 × 2), 1 above it.
- Primes 4 apart are called cousin primes, and 3 has one cousin: 7.
3 at a glance
- In words
- three
- In Roman numerals
- III
- Odd or even
- Odd: it ends in 3
- Triangular number
- 1 + 2 + … + 2 = 3, a triangle of counters with 2 on the bottom row
- Its factors add up to
- 4, or 1 without 3 itself, which makes 3 a deficient number
Related pages
More numbers
Questions parents ask
Is 3 one of a pair of twin primes?
Yes. Twin primes are two primes 2 apart, and 3 pairs with 5.
What is the next prime number after 3?
5, which is 2 more than 3. Every number in between has a factor other than 1 and itself.
What is 3 × 3?
3 × 3 = 9. The square of a prime has exactly three factors: 1, 3 and 9.
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.