The first Times Su Doku book sparked a worldwide publishing phenomenon - sales have topped 4 million copies worldwide since March 2005. A fifth collection of 100 previously unpublished puzzles from the man who started it all, Wayne Gould. Four levels of difficulty - easy, mild, difficult and fiendish - to challenge, stimulate and divert all Su Doku addicts. The Times Su Doku remains the original, the best and the market leader.