Sudoku puzzle solving methods

"The loner" or "last hero" method

The essence of the method

This method is fundamental in Sudoku puzzles solving. The main point is to find a cell in which only one value is suitable based on the values in the row, column and square (in which the cell is located).

Example

Let's look at the picture above and pay attention to the cell "9E", its area is highlighted in blue. Based on the values of the "E" column, in which the cell is located, we get variants of the values ​​"2" and "6", bsince only these values are not enough in the column. Next, consider the row "9", in which the cell is also located and see that the value "2" is present in this row. We concluded that the cell can take on only the value "6".

The “pair” and “triple” methods

The essence of the methods

The essence of the methods is to exclude unnecessary candidates from the cells. This method will help to open the cage, or simplify the further game.

Example of the "pair" method

Let's look at the picture above and pay attention to the column "A". Cells "A1", "A2" and "A3" have notes with possible candidate values. Because in cells "A1" and "A2" (highlighted green) only two identical candidates "3" and "8" are possible – we make the correct conclusion that a "pair" is found. Now we exclude the values of the candidates of the "pair" from the cell "A3" (also from all other cells of column "A" and square "1").

As a result, "A3" has only one candidate value "9" and we can open it, but this is another story :)

Example of the “triple” method

Cells "A1", "A2" and "A3" (highlighted in green) of column "A" have notes with possible candidate values. In these three cells, there are no other value candidates except for "3", "8" and "9". In total, in three cells there are three different candidates. We concluded that the "triple" is found. We exclude the values of these candidates from other cells of column "A" and square "1".

By analogy, you can search for “fours”.

The methods of "hidden pairs" and "hidden triples"

The essence of the methods

The essence of the “hidden pairs” and “hidden triples” methods is similar to the essence of the “pairs” and “triples” methods and is to exclude unnecessary candidates from cells. This method helps to simplify the game in the future.

Example

Let's look at the Sudoku square "3" (highlighted in blue). Candidates with the values of ​​"6" and "7" are only possible in cells "A8" and "A9"", because there are values ​​"6" and "7" in column "G" and rows "2", "3" (highlighted in pink). The correct conclusion is that we found a hidden pair of candidates "6" and "7" in cells "A8" and "A9". With confidence, we exclude other candidates from these cells.

Hidden triples" and "hidden fours" are searched by analogy.

About these methods

The above methods are basic, but having mastered them, you will have good skills for Sudoku puzzle solving. There are a large number of other logical methods for solving the puzzle. You can find them in print media dedicated to Sudoku or on the Internet.