Dr Gareth Moore is the author of over 100 puzzle and brain-training books for both children and adults, including The Mammoth Book of Brain Games, The Mammoth Book of New Sudoku and The Ordnance Survey Puzzle Book. He is also the creator of the daily brain-training website BrainedUp.com, and runs popular puzzle site PuzzleMix.com. Find him online at DrGarethMoore.com