Solving Classic Sudoku: 'Single Candidate'

This is a very easy and straightforward method of finding a number. Select a cell (preferably with many given numbers in the corresponding row, column and box). If there is only one possible number that could be entered in the cell, it has to be that number.

Take a look at Puzzle No.104. We select R2C5 as it has many given numbers in the corresponding row, column and box.


The selected cell is marked in green.


All the numbers in the corresponding row, column and box are marked in red.


As 1, 3, 4, 5, 6, 7, 8 and 9 are present in the corresponding row/column/box of the cell, the only possible candidate for the cell is 2.

Other Solving Techniques