Challenge yourself with number puzzles from The Times For anyone who loves the challenge of Su Doku but manages to solve them within minutes, you can now enjoy the extended mental workout and ultimate endurance test of a five grid interlinked system. This is Su Doku multiplied: every column, row and 3x3 box must contain the digits 1 to 9. Where the puzzles overlap, the rows and columns do not go beyond their usual 9x9 length but the interlocking boxes give you more clues - and more complexity. With another 100 new Samurai puzzles to vex you for hours, lose yourself in the four levels of this book: 10 Easy 40 Mild 40 Difficult 10 Super difficult Even the speediest of Su Doku solvers will be agonising over these ultra-complex, extended brainteasers. These are the most difficult Su Doku puzzles in The Times range. * from The Times, the No. 1 for Su Doku * The Times, as the premium brand, is the market leader in this area * this is one of the most challenging in The Times Su Doku range.