Welcome back to our Sudoku technique tutorial series! Today, we'll be diving into one of the most fundamental strategies you can utilise to solve Sudoku puzzles - the 'Naked Single' technique, sometimes also known as 'singleton' or 'lone number'.
So, What is a Naked Single?
A 'Naked Single' technique is a simple yet powerful method that fits perfectly into the Sudoku rules. When we consider an empty cell in a Sudoku puzzle, we should be able to find out what digits from 1 to 9 can potentially be placed there. This assessment is based on examining what digits have already been used in the common row, the common column and the shared 3x3 box of the empty cell in question. In some occasions you can rule out 8 out of 9 possible numbers, allowing you to place the number in the particular cell.
An Example of Naked Single Technique
Let's take an example to understand this concept better. Consider the following small Sudoku grid:We focus on the empty cell right at the center of the board, row 5 col 5. Compare which numbers are already placed either in row 5, col 5 or block 5. You will notice only the number 5 is not present yet, and is the only possible solution left for the cell, row 5 col 5.
We focus on the empty cell right at the center of the board, row 5 col 5. Compare which numbers are already placed either in row 5, col 5 or block 5. You will notice only the number 5 is not present yet, and is the only possible solution left for the cell, row 5 col 5.