Keen code breakers are in for a treat, as the Royal Mint has launched a fiendishly challenging puzzle. The Great British Treasure Hunt will set amateur sleuths across the country a series of increasingly challenging puzzles. Anyone who can solve all five levels of codes will earn the chance to win a solid gold bar worth over £28,000. However, you can attempt the first four questions right now, using just a few coins you might already have in your purse or wallet. Once you've solved that challenging test, there are still three more riddles to solve: Seven Siblings, The Constellations, and Newton's Heptagon.