Sudoku Single Cell MethodReturn to the Sudoku Home
The "Single Cell" method is the second step that most people use to solve Sudoku puzzles. By using this method along with the Single Solution method, all the easy levels can be solved.
The first thing you need to do is use the Single Solution method to place pencil marks into each cell corresponding to the possible values for that cell. Now, focus on one row. Look at the pencil marks for each empty cell in that row. If there is a pencil mark that only appears once, then that must be the solution for that cell.
In this example, we are inspecting the top row. Notice how the pencil mark 3 only appears once in that row. It must therefore be the solution for that cell.
You can repeat this process for each row, column and sub-square.
A variation of this method is to look for places where a number is forced. In the second example on the left, the green square must be a 3 because the 3 has nowhere else to go in the middle sub-square.