Killer puzzles uses the same grid as Sudoku and require the reader to fill in the numbers 1 to 9 as before. But this time the numbers in the outlined boxes must also all add up to a specific number.Already hugely popular in the national press, the puzzles are a must for Sudoku fans. With three difficulty ratings, from easy to hard, the 600 brand new Killer Sudoku puzzles in this book will provide a challenge to the most Sudoku addicted.Challenge yourself today!