A collection of 200 previously unpublished Difficult Su Doku puzzles of the highest quality from the Su Doku suppliers to The Times newspaper. Perfect for the intermediate Su Doku solver in need of a constant supply of challenging puzzles, this book is guaranteed to provide hours of absorbing, brain-stretching entertainment. Since the first Su Doku puzzle appeared in The Times in November 2004, they have become a phenomenon, with over 5 million copies of The Times Su Doku books sold worldwide. You don't need to be a mathematical genius to solve these puzzles; it is simply a question of logic. Each puzzle has a unique solution - and there's no guesswork required. The Times Su Doku remains the original, the best and the market leader.