Salient Features of This Gigantic Sudoku Game Book: No. of Sudoku Puzzles: 1600 (400 Medium, 400 Hard, 400 Difficult, 400 Insane) Sudoku Puzzles in 9X9 Grid Format Book Size: 8.5X11 inch, Suitable Sudoku Large Print For Seniors The number of possible 9X9 Sudoku grids is 6,670,903,752,021,072,936,960 which is very huge. That is why the Sudoku Puzzles created by us are all unique. Enjoy playing this Sudoku Best Brain Book for Adults. Contains Sudoku Puzzles for Adults, Sudoku for Seniors These Sudoku Brain Games are Expertly Crafted for Sudoku Lovers Regularly Playing Sudoku helps keep and maintain your Brain Young and Active, because Sudoku Game Challenge Your Brain. As You Play Sudoku Medium to Hard, Sudoku Hard, Sudoku Very Hard, Sudoku Hardest, Sudoku Toughest, You will soon grow out as a Sudoku Genius. This Book Best Describes itself and is surely for you, if you are looking for sudoku Challenging, Sudoku for Adults, Sudoku Puzzle Book for Adults, Sudoku Puzzles Hard, Sudoku Difficult Level, Sudoku Hard to Extreme, Sudoku Expert, Sudoku Extremely Difficult, Sudoku Extremely Hard, Sudoku Difficult, Sudoku Extreme, Sudoku for Dummies, Sudoku Insane, Sudoku Book Hard, Sudoku Large Print Hard, Sudoku Spectacular If You are looking for Sudoku with over 500 puzzles, Sudoku with over 900 puzzles or Sudoku with over 1000 puzzles, then look no further, just grab this Sudoku Medium to Hard Large Print as it contains Sudoku with over 1500 puzzles.