How to Solve a Sudoku
Understand the rules., Seek "definites"., Work your way through the numbers until 9., Look again when stuck., Start by doing Sudoku in the newspaper or online (see links below)., Try your hand at harder Sudokus.
Step-by-Step Guide
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Step 1: Understand the rules.
Each row, column, and 3 by 3 square must have the numbers 1 through
9.
These numbers can't be repeated in each row, column, and square.
Certain Sudokus will specify if the diagonals also must have the numbers 1 through
9. -
Step 2: Seek "definites".
When solving an easy Sudoku, the first thing you should do is look for definites.
Definites are numbers that are definitely going to be there.
Starting at 1, draw imaginary lines through boxes in that 1's row and/or column.
When there is only one box left in the 3x3 box, you know that is a definite. (See images one and two.) , Since you have filled in some numbers, this should help get other numbers that had more than one possibility before. (See images three and four.
Notice how the 3s could not have been solved before, but are solved in the final). , If you get stuck, go back and make sure to look at everything.
It is almost guaranteed you missed something.
That one number is usually all you need to get going again.
If you still cannot find any solutions, start labeling every block with every number that could possibly go in that box.
For example, in image one, all the empty boxes have numbers that could possibly go there.
Fill these in.
If there is a 1 in the row or column of that box, you know that 1 is not a possibility. , The newspaper sudokus are usually easier on Monday and Tuesday.
The difficulty increases as the week passes. , This particular Sudoku (images one through four above) could be solved with only definites, but what do you do if it can't? -
Step 3: Work your way through the numbers until 9.
-
Step 4: Look again when stuck.
-
Step 5: Start by doing Sudoku in the newspaper or online (see links below).
-
Step 6: Try your hand at harder Sudokus.
Detailed Guide
Each row, column, and 3 by 3 square must have the numbers 1 through
9.
These numbers can't be repeated in each row, column, and square.
Certain Sudokus will specify if the diagonals also must have the numbers 1 through
9.
When solving an easy Sudoku, the first thing you should do is look for definites.
Definites are numbers that are definitely going to be there.
Starting at 1, draw imaginary lines through boxes in that 1's row and/or column.
When there is only one box left in the 3x3 box, you know that is a definite. (See images one and two.) , Since you have filled in some numbers, this should help get other numbers that had more than one possibility before. (See images three and four.
Notice how the 3s could not have been solved before, but are solved in the final). , If you get stuck, go back and make sure to look at everything.
It is almost guaranteed you missed something.
That one number is usually all you need to get going again.
If you still cannot find any solutions, start labeling every block with every number that could possibly go in that box.
For example, in image one, all the empty boxes have numbers that could possibly go there.
Fill these in.
If there is a 1 in the row or column of that box, you know that 1 is not a possibility. , The newspaper sudokus are usually easier on Monday and Tuesday.
The difficulty increases as the week passes. , This particular Sudoku (images one through four above) could be solved with only definites, but what do you do if it can't?
About the Author
Nancy Hart
Brings years of experience writing about cooking and related subjects.
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