Other Sudoku Strategies

All of the Sudoku tips we have covered thus far involve the process of elimination. It is also good to remember that there is only one solution to every Sudoku puzzle. Keeping that in mind, let’s look at a couple other ways to go about approaching a Sudoku puzzle.

One strategy is to look at the 9 x 9 puzzle as a whole and then work down to an individual cell. Start by looking at the 9 x 9 puzzle area and the cells which need to have numbers inserted. You can choose any number 1 - 9 and look for it in each of the columns. For instance, if you chose the number 2, and you can see a number 2 is already in two columns, you can logically assume that it needs to go in the only column where it is absent.

As to where in that particular column the 2 needs to be placed is another story. Since every 3 x 3 block of the grid has to have one number 2, take a look at the 3 x 3s. Because two columns already had the number, it means that only one 3 x 3 square will be without the number. Check the rows within the 3 x 3 square to see if any have the number 2.  If they do you can eliminate that particular cell. If you already have a number in the second of the three cells, that leaves only the last or third cell for your number 2.

While the these Sudoku tips have concentrated on looking at the 9 x 9 grid as a whole and then narrowing the area of focus down to one cell for the number, the opposite can also be accomplished. This means starting out with an empty cell and expanding outward until the whole 9 x 9 is filled.

So, you begin this strategy by choosing one empty cell. It is best if there are a number of “givens” or numbers you have already filled in around it. After you choose your cell, look at its position within its smaller 3 x 3 block or region. Note all of the numbers already known in this area as a number 1 - 9 can only be used once in the 3 x 3 block. If this 3 x 3 square already had the numbers 4, 8 and 9, you would know for sure that your chosen cell will not be able to use one of these numbers.

Then move from the 3 x 3 block to look at the rest of the row. If it has other numbers, these can also be eliminated as they can only be used once in the row as well. Perhaps you found numbers 1, 3 and 6 also in the same row. That would be great because it means that your chosen cell will have to contain one of the four remaining numbers.

Proceed onward by looking at the column in which your chosen cell is situated. As we know, that a column can also only contain the numbers 1 - 9 once, if the numbers 2 and 7 are in the column, you will know immediately that the number 5 is the correct one to be placed in your chosen empty cell. The process of elimination comes into play a lot when you are working on a Sudoku puzzle.

So, give some of these Sudoku tips a try and see if you can make advances in your level of play. There are so many very complicated Sudoku puzzles coming out every day, you will not run out of new ones any time soon.