A Sudoku puzzle is played on a 9x9 grid, which is partially filled with digits from 1 to 9. We need to fill in all other empty cells with digits according to the Sudoku rules. So how do we decide what digit to fill in each empty cell? There are two basic methods that can help us make the decisions.
These two methods are essential for solving any Sudoku puzzle. You can use these two methods alone to solve an easy puzzle. But for a more difficult puzzle, you may encounter a situation where there is more than one possible cell for any digit that is not in a 9-cell unit yet, and there is more than one candidate for any empty cells in the grid. So, you cannot apply these two basic methods to solve the puzzle any more. In that case, you will need more advanced techniques. Advanced techniques are based on some logical reasons to rule out some possibilities so as to achieve a situation where two basic methods can be applied again. Mastering a variety of advanced solving techniques can help you solve more difficult Sudoku puzzles. Hopefully, this set of tutorials we provide here can help you achieve this goal.
If you are new to the Sudoku game, we have some tips for beginners. After you are familiar with the Sudoku rules and the basic techniques, you may come back here to learn more techniques.
The Sudoku solving techniques are summarized in the list below, and the order is generally from the most basic techniques to advanced techniques. After learning all these, you can enjoy the fun of solving challenging Sudoku puzzles.