This is on the back of the book: 100 fun and easy KenKen puzzles that use addition, subtraction, multiplication and division. Puzzles range from 4×4 to 6×6 grids. My review: There are 64 easy 4×4, 16 easy 6×6 and 20 Moderate 6×6, so if you are looking for “Easy to Hard”, this book is not for you. Poor quality paper, too.