Last remaining cell technique

Strategy #2 for solving Sudoku: The last remaining cell

The last remaining cell is a basic Sudoku technique that both beginners and puzzle gurus should know and understand. Virtually any simple Sudoku puzzle can be solved using this straightforward strategy. For complex Sudokus, this technique helps in the initial stages of the game and when you need to make candidate assumptions for cells. 

The essence of the strategy is as follows: each digit that is known to us on the game field creates areas on the game field where this digit can no longer be repeated. This helps us to exclude cells where the current digit CANNOT BE USED. This technique works when in a 3 by 3 square, some cells are already filled, and some cells cannot accept this digit, leaving only one cell that can take the value of the current digit. We place the sought-after digit in this cell, thus getting closer to solving the puzzle. 

In the image above, you can see the cells highlighted in red; these cells cannot contain the number 1. The top-right 3x3 block already contains the values 2 and 4, so only one cell remains where the number 1 can go in this square, and it is marked in green.

Apply this technique in practice, preferably starting with solving simple Sudokus. We wish you success in solving puzzles on Escape Sudoku.