Last free cell technique

Strategy #1 for solving Sudoku: The last free cell

The last free cell is the simplest and most elementary technique in Sudoku that all beginners need to know. Knowing this trick will help you solve simple puzzles for children or tackle any Sudoku puzzle in the final stages. 

According to the rules of Sudoku, each row, column, and 3x3 block must contain a complete set of numbers from 1 to 9. Therefore, if there is a last unfilled cell in a row, column, or 3x3 square, you can easily place the missing digit among 1, 2, 3, 4, 5, 6, 7, 8, 9 into it.

In the example above, you can see the game board where in 4 places you can use the "Last Empty Cell" strategy (highlighted in yellow). These cells are part of: a 3x3 square (highlighted in red), 1 column (blue), and 2 rows (pink and green rectangles).

For your convenience, numbers are written on the right and left to help you understand which digit is missing in the current area. If you understood everything correctly, then the numbers 3, 8, 9, 2 should be written in the places of the yellow cells. 

If you are just starting to learn Sudoku, we recommend playing Sudoku online in 4x4 or 6x6 grids and practicing the "last empty cell" technique.