Acclaimed Japanese mathematics instructor Tetsuya Miyamoto developed KenKen in 2004 and it has since taken over the puzzling world.It takes a page from karate, another Japanese art, as each title is graded by colour: White for easy, Green for medium, Brown for hard & this one, Black Belt, for the super-tough!All in a handy-sized format, so puzzle lovers can play this addictive game wherever the mood takes them!Are you experienced? These are the hardest KenKen for super-solvers only!Acclaimed Japanese mathematics instructor Tetsuya Miyamoto developed KenKen in 2004 with the goal of improving his students' math and logic skills.This understandable, fun and challenging puzzle quickly became a favourite leisure activity for all ages throughout Japan and then for millions of players worldwide.Now it's carried in the "New York Times", "Los Angeles Times", "Chicago Tribune", "The Times", "Scholastic" classroom magazines and more.This book contains 300 puzzles.