The method Naked Single is the simplest method we all use when we solve Sudoku. We simply observe that
a given cell has all but one 1-9 numbers as neighbours (either in row, column or square). Therefore, there
is only one possibility for the given cell.

Consider the green cell **I4** in the following example. It “sees” **1**, **2**, **6** and
**7** in the same row, **5**, **4** and **8** in the same column and **1** and **3**
in the same square. It can be neither of these values, so the only possibility left for this cell is **9**.

Load in Solver

Let us look at another example. The cell **B4** has neighbours **5**, **4**, **2** (row),
**7**, **8**, **3**, **1** (column) and **7**, **9**, **4** (square).
The only possible value left for **B4** is **6**.

Load in Solver

When you have the candidates option turned on, a Naked Single is simply a cell with only one possible value in it.

Load in Solver