There is an unwritten rule that sudoku puzzles must have only one solution. For this reason, some people consider puzzles with less than a certain number to be “unsolvable.”
If you’re looking for a way to improve your critical thinking and problem-solving skills, look no further than these five books!
Do you love a challenge? If so, sudoku is the perfect game for you! This puzzle game can be enjoyed by people of all ages and skill levels.