Sudoku Puzzles: Over 500 Hard Sudoku puzzles for adults (with answers)

Would you like to increase the effectiveness of your brain while you have fun? Increase the effectiveness of your brain function with Sudoku puzzles. What if you could reduce your chances of Dementia or Alzheimer's disease by solving Sudoku puzzles? According to the University of Edinburgh, UK, research has found that Sudoku can trigger "survival genes" in the brain that normally lay dormant. PencilPress team has been compiling and publishing puzzles for over two decades. By using his colle...