Naked Single
beginnerWhen a cell has only one candidate it is called a Naked Single. The digit must be placed in that cell.
Naked Single is a basic Sudoku strategy. It occurs when only one digit remains possible for a specific cell.
See the examples below for a clearer understanding.
Example 1
Check the image below. 8 is the only digit that can go in cell A7. Digits 1 to 6 cannot be placed in A7 as they already appear in row 1. Similarly, 7 and 9 cannot go in A7 because they are already present in column 7. Therefore, the only valid digit for A7 is 8.
Example 2
Look at the image below. The only digit that can go in cell C1 is 6. Can you figure out why?
Example 3
This example is a bit more challenging. In addition to the classic Sudoku rules, this board also follows the Non-consecutive Sudoku rules. The Non-consecutive rule states that adjacent digits (above, below, left, or right) cannot be consecutive.
Looking at the image, F5 is a Naked Single and can only contain the digit 5. Digits 2, 4, 6, 8, and 9 cannot go into F5 due to the classic Sudoku rules. 1 and 3 are eliminated because they are adjacent to the digit 2. 7 cannot be placed in F5 because it is adjacent to 8.
The only remaining valid digit for F5 is 5, which is placed in the cell.
Practise this strategy with built-in step-by-step hints inside our apps.