How to Solve Sudoku in Less Than 10 Minutes

Logic-based Sudoku puzzles can become addictive.

Sudoku is a logic-based number puzzle. Each vertical and horizontal row, along with each nine-square block of the puzzle, contain one instance of the numbers 1 through 9. Each puzzle shows you only a few numbers in each row or column, leaving you to fill in the remaining blank boxes. Trial and error will get you the rest of the numbers, but with a systematic approach, you can solve Sudoku puzzles in less than 10 minutes.

Things You'll Need

• Pencil
• Eraser

Instructions

1. Begin in the upper left corner of the puzzle. In each blank space, write the numbers one through nine in the box with pencil, three numbers across in three rows. Continue with all the blank squares in the puzzle.

2. Start in the upper left corner with the first number clue provided by the game. Since each row, column and nine-square box can contain that number only once, you can eliminate that number from the blank squares you numbered in the previous step. Work systematically across that row, erasing that number from each blank square. Repeat for the column and for the nine-square box containing that number. After completing each row, column and box, check the numbered box so you know you've completed that number.

3. Repeat this process for each number clue of the Sudoku puzzle. By working systematically with the numbers shown and erasing the numbers from your penciled in numbers from Step 1, you will be left with the remainder of possible combinations of numbers that could be left in the blank squares.

4. Analyze the remaining penciled numbers in each blank box. Where only one number is left in a blank square, that is the number for that square. Circle the small number and repeat the process of checking each row, column and nine-square box for that number. Mark it as checked when you've finished. Repeat for any other squares with only one number.

5. Review the remaining blank squares that have more than one penciled number remaining. At this point you will likely have to resort to trial and error, but you should be able to complete the puzzle with the numbers left in the blank squares.

References

• University of Texas at Austin Computer Science Department: The Science of Sudoku