- Over het boek Sudoku has become an enormously popular pastime, and is by now as popular as crosswords and cryptograms. One encounters sudoku-puzzlers everywhere: in waiting rooms, on the beach, in the plane. Therefore one can rightfully claim that sudoku is the puzzle of the 21st century. Where crosswords require a large vocabulary, sudoku requires a wealth of solution techniques. This book discloses a number of techniques that will enable the reader to solve every sudoku puzzle. A multitude of worked examples and exercises takes the reader by the hand, providing ample experience and confidence, so that one can tackle the most difficult sudokus in newspapers, in puzzle magazines and on the internet. The book has several unique features. The use of number pairs is unique, and it forms the basis for all steps in the solution process. Other books invariably recommend denoting all remaining possibilities in every empty square, leading to quite a mess and costing unnecessary time. In Solve every sudoku this laborious process is avoided completely. This is not only much easier and more natural; it turns out also to be much more effective! Another unique feature is the way of coping with the most extreme sudokus described at the end of the book. The alternative presented here for extremely difficult puzzles is entirely novel! The reader will notice that his level will increase with ease when going through the various chapters. Every step in the process enables the reader to solve even more difficult sudokus. After 7 steps the reader will be able to solve puzzles that are characterized as very difficult. Steps 8 and 9 are meant for extremely tough sudokus, but the techniques required have also been described clearly, with ample examples and exercises. The reader is advised to go through the methods step by step, and after step 7 to first buy some magazines to test his/her newly acquired skills. Also for sudokus we have that practice makes perfect! Over de schrijver Wil Schilders studied mathematics in Nijmegen (NL) and Dublin (IRL), and is now employed at NXP Semiconductors as well as a professor of numerical mathematics at Eindhoven University of Technology. He uses mathematics to solve practical problems, especially from the electronics industry. In 2004 he started to get interested in sudoku. On his frequent international business trips he regularly bought sudoku booklets and magazines, thus acquiring quite a bit of experience. As a mathematician, one is always interested in a guaranteed way of finding or developing methods to solve as many sudokus as possible. Besides this aspect, there is also the didactical side. Many will agree, when thinking back about secondary school, that it is really an art to present mathematics in a clear and comprehensible way, understandable for everyone. In his daily work, he does this in his lectures at university, where advanced mathematical methods are explained in an appealing way and with much enthusiasm. This was also one of the motives in writing this book: a clear approach, worked examples with many useful and exercises, everything that is needed to impart the reader with the art of sudoku solving. What can be more exciting than teaching others ones own experiences!