What are prime numbers?
A prime number is a number that cannot be generated by multiplying any 2 whole numbers (aside from 1 and itself). For example, 8 is not a prime number because you can get it by multiplying 4X2. 7 on the other hand IS a prime number because there are no whole numbers you can multiply to generate it aside from 1X7.
Three are infinitely many primes and every number can be
expressed as the product of primes in exactly one except for the
order of the factors.
A prime number is any number that has only 2 distinct (different) factors, namely 1 and itself.
- 7 is a prime number since the only factors of 7 are 1 and 7
- 6 is not a prime number since it has the factors 1, 2, 3 and 6.
1 is not a prime number since, although it is only divisible by 1 and itself (as itself is 1) it does not have two distinct (different) factors - it has only one factor: 1. The number 1 is called a Unit.
Numbers which are not prime (except for the number one) are called composite numbers, for example 6 is a composite number.