Book excerpt: Sharpen your pencils–and your wits–there’s a new puzzle in town. Millions of Sudoku fans around the world are discovering a brand new addiction: the brain-buster Kakuro. Combining the appeal of a crossword with the addictive properties of Sudoku, it’s the latest puzzle craze to come from Japan. Kakuro is more challenging, more compulsive, and more fun than anything you’ve played before. Includes: 50 Easy, 50 Medium, and 50 Hard puzzles Rules, Tips and Strategies A "unique sum chart" that is the key to unlocking the logic of Kakuro