3Here is the perfect collection of hard puzzles for adults and for avid Sudoku fans. So grab a pencil and enjoy hours and hours of magnetic puzzles for adults solving Dive into the puzzling craze with this gigantic collection of fun puzzles for adults This cool Sudoku big book contains 400 Hard Sudoku puzzles 6 by 6 that is great for advanced Sudoku lovers. The 6 by 6 Sudoku puzzle is played exactly the same way as the standard Sudoku- you have to put the numbers so that they appear only once in each row, column, or block. 6 by 6 Sudoku puzzles are little bit easy than 9 by 9, so they are suitable younger people or if you just do not have much time to play. Solving puzzles such as Sudoku keep the brain active, improve your number analyzing skills. Solving Sudoku's with elimination strategies rather than guessing make us smarter. Enjoy the game Features of the product:400 Hard Sudoku puzzles for hours of enjoyment.Big grids for easy solving.Handy- sized Hard Sudoku books for adults are perfect for trips and traveling.Every Sudoku puzzle is designed so that there is only one solution. Pre- checked manually.Great challenging entertainment for advanced Sudoku solvers.