Prime numbers can only be divided by themselves and 1. Find out how to work out if a number is a prime in this Bitesize Primary Second Level Maths guide.

The online computer game “Is this prime?” tests a player’s knowledge of prime numbers—and just surpassed 2,999,999 attempts. Give it a whirl.

For the first time in more than 25 years, mathematicians have proven a new way to identify prime numbers, and in doing so developed a toolkit that could allow further advances in number theory.

A basic feature of number theory, prime numbers are also a fundamental building block of computer science, from hashtables to cryptography.

Today, people use complex computing networks to search for prime numbers with millions of digits. But early mathematicians were running these calculations by hand.