Description Sudoku Progress Chart Sudoku Rules and Solving Methods LEVEL 4. Focus on the hidden numbers LEVEL 5. Focus on the rows and columns LEVEL 6. Find clues in the blanks where the number isn't fixed yet Wait! Before You Give Up on a Puzzle... Answer Key Editor's Note Sudoku That Feels Satisfying to Solve — Praised by Our Beta Testers! The beta testers who solved and verified the puzzles in this book fell completely in love with Sudoku, saying they plan to keep enjoying it as a hobby going forward. Beginners who didn't even know the rules of Sudoku experienced both fun and a sense of accomplishment as they worked through the easier puzzles, while those already familiar with Sudoku felt a great sense of achievement as they progressed through increasingly challenging levels. We hope readers, too, will feel the irresistible pull of Sudoku — the kind that keeps you coming back for more — and turn it into a productive hobby all their own.