In , sub-regions have specified sums, and no number can be repeated within a region. This variant also called " ", " ". is a puzzle that combines elements of and . Regular 9x9 Killer Sudoku that row and column rules apply, but instead of a 3×3 grid they are nine Jigsaw shapes. Despite the name, the simpler killer sudokus can be easier to solve than regular sudokus, depending on the solver's skill at mental arithmetic, the hardest ones, however, can take hours to crack. In Killer Sudoku, sub-regions have specified sums, and no number can be repeated within a region. The puzzle book contain: - 200 Puzzles - Handy 6 x 9 inch Book Layout - 2 Puzzles per Page - Ideal for Beginners In the book you will find a description and examples of solutions for all puzzles. The book is for those who like logic and math problems. Decide, developing and improving.