The Times Samurai Su Doku 13: 100 extreme puzzles for the fearless Su Doku warrior

Challenge yourself with number puzzles

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 1...