Obvious singles technique

Strategy #4 for solving Sudoku: Obvious singles  

In this article, we will talk about the "Naked Single" strategy. This technique will help you solve medium and hard Sudoku puzzles. Naturally, knowing only this technique will not enable you to solve difficult Sudoku puzzles, but in combination with other strategies, you can find solutions to puzzles very quickly.

So, this strategy involves finding a cell that can only contain one digit. To do this, you need to fill in all possible digit combinations for all empty cells on the game board. If you find such a cell, confidently place the only possible digit in it.

We want to draw your attention to the fact that to use this trick, you will need to use notes. For offline Sudoku, these can be pencil marks in the cells. And for online Sudoku, there is a special mode that needs to be activated to enter possible candidates for the cell. To switch to this mode on our website, simply click the "NOTES" toggle or press the "ENTER" key on your keyboard.

In the example above, we have filled in all the cells of the Sudoku game board with possible digit candidates for these cells. As can be seen from the image, some cells have only one entry in the notes (highlighted in yellow). Accordingly, these cells can only accept this value, so they can be filled in immediately.

As we can see, this is just one of the techniques for solving Sudoku, but it is very helpful in certain situations. Want to apply the theory in practice? - Then we recommend playing medium Sudoku.