Active Brain Series giant book of 1200 hard Sudoku puzzles with solutions, perfect for the more experienced, or adventurous. With only one level of difficulty there are no wasted puzzles. Sudoku is a fun way to exercise your brain and there are plenty of puzzles in this book to give it a really good workout! The book is 8.5" by 11" and has 4 puzzles per page with room for notes.