200 of the original number-placing puzzles.

Su Doku 'the crossword without words' comes with a health warning: it is seriously addictive.

Here is a collection of 200 su doku puzzles taken from Times Su Doku books 1 & 2 and ranked in order of difficulty, from easy to fiendish. They have been created by Wayne Gould who sets the puzzle for The Times.

Wayne Gould is the brains behind Su Doku. A former High Court judge in Hong Kong, he now spends his time developing the puzzle.

You don't need to be a mathematical genuis to solve the puzzles; it is simply a question of logic.