SUDOKU Extremely Hard: - Sudoku Games Book For Adults Killer Gamers Sudoku Master Challenging, 1 Puzzle per Page, Special Bonus Included is one of the best Sudoku for you to practice it as much as you want. - Pocket Size: It is designed in pocket book to carry everywhere you go.- 100 Puzzles: It is included with 100 Very Hard Sudoku Puzzle- Room to Play: As it is printed 1 Puzzle per Page, there is available room for you to jot down your thinking.- SPECIAL BONUS: 50 Randomly Games including from Beginner, Intermediate, Hard and Extremely Hard to challenging you to make it done faster.