Einstein devised a riddle when he was a child. He predicted that only 2 per cent of the world's population would be able to solve it. Can you? Q: There are five houses painted five different colours. A person with a different nationality lives in each house. The five house owners each drink a certain type of beverage, play a certain sport and keep certain pet. No owners have the same pet, play the same sport or drink the same beverage. The Facts: The Briton lives in the red house. The Swede keeps dogs as pets. The Dane drinks tea. The green house is on the left of the white house. The owner of the green house drinks coffee. The person who plays football rears birds. The owner of the yellow house plays baseball. The man living in the centre house drinks milk. The Norwegian lives in the first house. The man who plays volleyball lives next to the one who keeps cats. The man who keeps the horse lives next to the man who plays baseball. The owner who plays tennis drinks beer. The German plays hockey. The Norwegian lives next to the blue house. The man who plays volleyball has a neighbour who drinks water. So, WHO OWNS THE FISH? A fiendishly clever little problem, Einstein's riddle requires the coolest application of logic and lateral thinking. But solving it is just the first of many challenges. Here are some of the most mesmerising conundrums ever conceived. Whether you're pondering 'The Librarian's Dilemma', puzzling over 'The Sleeping Beauty Problem' or unravelling 'The Gambler's Mistake', this book will exercise your grey cells and keep you guessing from beginning to end.