3You don't need to be a mathematical genius to solve the treacherous puzzles in this collection of Fiendishly difficult puzzles, it's simply a question of logic. Since the first Su Doku puzzle appeared in The Times in November 2004, this classic game of logic has become a phenomenon, with over 5 million copies of the Times Su Doku series sold worldwide. Perfect for the advanced solver in need of a constant supply of ultra-difficult puzzles, and guaranteed to provide hours of mind-stretching entertainment.