Sudoku Jigsaw (also known as " Irregular ", " Nonomino " or " Geometric Sudoku ") is a logic-based, combinatorial number-placement puzzle. Jigsaw Sudokus are very similar to regular Sudoku puzzles. Regular 9x9 Sudoku that row and column rules apply, but instead of a 3x3 grid they are nine Jigsaw shapes. The puzzle books series contain: - 250 Easy Puzzles - 250 Normal Puzzles - Handy 6 x 9 inch Book Layout - 6 Puzzles per Page - Ideal for Beginners The book is for those who like logic and math problems. Decide, developing and improving.