Killer Sudoku Adventures volume 2 book features 500 Puzzles of Killer Sudoku that will take you into an adventure of 10 Difficulty levels from Easy to Medium. Answers to all the puzzles are included at the end of the book. Killer Sudoku unique sum cheat sheet included inside the book What is killer Sudoku and how to solve? Killer Sudoku tests your arithmetic skills. It was scientifically proven that mathematical games keep your brain active and help to fight neurodegenerative diseases. - For Killer Sudoku: it starts with an empty grid and only given the sum of caged cells written in small font on the upper left corner of the cage. - No number can be repeated in any row, column, region or cage. You have to work out the summation and find the numbers in the cage, region, row, and columns. - Of course, you will use every tip and trick used for traditional Sudoku and more. - There are many tips to solve traditional Sudoku especially elimination and exclusion and logic. But for killer Sudoku, the rule of 45 and unique sum are the most important clues to solve the puzzles. What is the rule of 45? Every row has a sum of 45, and every column has a sum of 45 and every region has a sum of 45. What is the rule of the unique sum? Because numbers cannot be repeated in any cage, that makes some numbers have a unique sum. E.g. 4=1+3 as 2+2 is not possible. More instruction and tips can be found inside the book. Features: Size: 8 x 11.5 inch (large size) with softcover and paperback binding so easy store and use. - Pages: 174 pages with four puzzles per page. Total 500 different puzzles. - Plus the solutions of all the puzzles at the end with Killer Sudoku unique sum cheat sheet included. Solving Killer Sudoku puzzles is a travel adventure between the numbers, are you ready? Scroll up and order your copy.