Before I talk about the Sudoku techniques, I should let you know that, there are actually just 2 techniques: Pointing Out and Fitting In. In this post I will talk about the Pointing Out technique, in Easy level.
Look at the board below, focusing on box 1. There are six empty cells in box 1, seems clueless, but notice there is a 5 in row 1, so no other cells in row 1 can be 5, and there is another 5 in column 2, so no other cells in column 2 can be 5. Now image the two 5s can beam light, both pointing to box 1 (you can click on the board to see the animations, yes, the board is clickable!).
As you can see, the lights from the two 5s pointing to box 1 highlight the five of the six cells that cannot be 5, the only cell left out must be 5, so the solution is 195. (What is 195? see Sudoku Rules and Terminology)
The next solution is 761 in box 7, click the board to see the animations.
Now you can see how Pointing Out technique works, you focus on a target unit, image cells (with the same number) around it beaming lights to the target unit, if only one cell left out in the target, the number must go to that cell.
Of course not only a box, a column or a row can be a target unit too. See the board below.
Target unit: row 1, solution: 331
More examples, Pointing Out in a clean box:
Five pointers pointing to a row:
That's the very basic Pointing Out technique, as simple as it is, all the Easy level puzzles you can find in newspapers and websites, can be solved using this technique alone.
Sudoku Rules and Terminologies
Technique No.1 Pointing Out - Easy Level
Technique No.2 Pointing Out - Medium Level
Technique No.3 Fitting In - Medium Level
Technique No.4 Fitting In - Hard Level
Technique No.5 Pointing Out - Hard Level
Technique No.6 Pointing Out - Expert Level
Technique No.7 Fitting In - Expert Level
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