The Single Strategy
Make you custom with the nomenclature used in our tutorials
If you are completely new to sudoku, you will get an explanation of the simple rules for a standard sudoku containing 81 cells (9 rows x 9 columns) here. You can see all sorts of sudoku variations around, but this is the most common one and it's the one you can solve direct on this web site or print if you use the Home button in the menu above.. First we will explain the nomenclature that will be used in future published tutorials. See image 1 below.
Candidates are numbers in empty cells like the small numbers in the image below. They are there to show what numbers can go into an empty cell. When you solve a Sudoku by using candidates, it's all about eliminating the candidates. There are a lot of strategies for doing that. The Single Strategy is one of them and described here.
The Single Strategy
A single is easily spotted if you are using Candidates in the empty cells.
When there is a candidate, like the red number 2 in the image above, which is the only number two in a box, row or column, that number 2 candidate is a single and you know that 2 is the right number for that cell. That means that you can just eliminate the other candidates (green 7 & 8) in that cell. The number 2 is now the real number in the cell.
There are no ramifications of this in other cells in this box. You are left with four empty cells with the candidates 18, 178, 19, and 79. Usually when you apply a strategy like this, it opens up for other strategies. That is not the case here. We can only leave this box as it is for the moment.
There may be ramifications of this outside this box, in other cells in the Sudoku. The cell with the red number 2 has now the real number 2 so you can eliminate all number 2 candidates in the row and column this cell is a part of.
I hope this explained the Single Strategy so you have an understanding of how It works. Don't hesitate to bookmark this article, we may come back here later to ad a few more examples. For the moment you can just click or tap Home in the menu so you can solve a Sudoku Puzzle. Maybe you can apply the Single Strategy. Thank you for reading this and good luck!
About the author: Olov Forsgren is a retired software engineer with lifelong experience in marketing. He has been in network marketing over six years. His hobby is social media marketing and attraction marketing. His 80K+ followers on Twitter, 2,5K+ friends on Facebook and 7K+ followers on Google Plus indicates that he even master the most modern social marketing techniques.