Of the seven Millenium Math Problems, each of which is worth $1 million (£600,000) to the person who can solve it, the Riemann hypothesis is perhaps the most difficult to crack. Reckon you've got what it takes?
In this video, my favourite mathematician, Edward Frenkel, explains the basics of the theorem. The video is a little lengthy at around 17 minutes, but the fascinating explanation provided by Frenkel will keep you engaged. If you can puzzle through it, you could make yourself a packet—but it might just be the hardest $1 million you ever make. [YouTube]