prime number
The prime numbers are the atoms amongst the integers, and while we know that there are infinitely many of them, there's no general formula that generates them all. Julian Havil looks at a littleknown algorithm that sieves out all primes up to a given number, and which is astonishing in its simplicity.

The primes are the building blocks of our number system, but there's no general formula that will give you all of them. If you want them, you have to hunt them down one by one. Abigail Kirk investigates a method that does just that.



The Great Internet Mersenne Prime Search strikes again


It has often been observed that mathematics is astonishingly effective as a tool for understanding the universe. But, asks Phil Wilson, why should this be? Is mathematics a universal truth, and how would we tell?

Following on from his article 'The prime number lottery' in last issue of Plus, Marcus du Sautoy continues his exploration of the greatest unsolved problem of mathematics: The Riemann Hypothesis.
