Sudoku Single Solution MethodReturn to the Sudoku Home
The Single Solution method is the first step that most people use to solve Sudoku puzzles. Many of the easy levels can be solved entirely using this method. This method is also known as the Naked Single, Sole Candidate, or SiSo method.
The first thing you need to do is focus on an empty cell. Use pencil marks to mark every possible number that could go into that empty cell. You will need to look at the row, column and sub-square to determine which numbers can go into the empty cell.
In the first example to the left we are examining the yellow square. By looking at the row, we can eliminate numbers 2 and 3. By looking at the column we can eliminated 7, 5, and 6. By looking at the sub-square we can additionally eliminate number 8. Now, we know that the yellow square may only contain the numbers 1, 4 or 9. You can use pencil marks to indicate this information.
If you determine that only one number can fit in a cell, then you have solved it. In the second example we can eliminate everything except the number 9, so we have found the solution.
When you have examined each cell once, you will need to go back and try again. Usually the entire puzzle can be solved in 2 or 3 iterations.