There's been progress on one of the biggest open problems in maths: the twin prime conjecture.

Number theory is famous for problems that everyone can understand and that are easy to express, but that are fiendishly difficult to prove. Here are some of our favourites.

In 1998, Goldbach's Conjecture was shown by computer to be true for even numbers up to 400,000,000,000,000. In addition, some progress has been made towards formally proving the conjecture. As of this year, mathematicians with Goldbach fever have some extra incentive for their labours.

Since we first wrote about the Goldbach Conjecture we've had many requests for more information about  it and about how our Goldbach calculator works. We answer some of your questions here but the Goldbach conjecture touches on a strange area of maths that may leave you even more curious than before...

Can every even number greater than 2 can be written as the sum of two primes? It's one of the trickiest questions in maths.