# How is Sudoku played exactly? **URL:** \ **Category:** Factual Questions\ **Created:** [March 18, 2006, 8:12am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883 "2006-03-18T08:12:24Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![ParentalAdvisory](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@ParentalAdvisory](https://boards.straightdope.com/u/ParentalAdvisory)\ **Post date:** [March 18, 2006, 8:12am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883/1 "2006-03-18T08:12:24Z")
The Objective states: > [@](#): > > Fill in the puzzle so that every row, every column, and every 3 x 3 box contains the numbers 1 through 9. Either this is really easy, or I’m a complete fool. I still don’t get it. Everytime I start to put in numbers, the number shows up in an unrelated 3x3 square on the other side of the puzzle. What is that about? How do I play this game? ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [March 18, 2006, 8:33am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883/2 "2006-03-18T08:33:59Z")
You have to get numbers 1 through 9 ( 0 is excluded) used ONLY ONCE in every row, column and 3_3 square. To fill in the blanks, observe what numbers have already been used up in a particular 3_3, row, and column. Its a process of elimination. Observe: 3 2 ( ) 9 ( ) (_) ( ) 6 4 ( ) ( ) ( ) ( ) ( ) 1 5 ( ) ( ) ( ) ( ) 8 ( ) With this simple ASCII fragment sudoku containing a row, column and 3_3 square, you can see the space with the asterisk is meant to be a 7. Using the process of elimination with other rows, columns, and 3\*3s you can fill in all the blanks. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [March 18, 2006, 8:34am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883/3 "2006-03-18T08:34:53Z")
> [@ParentalAdvisory](#): > > The Objective states: > > Either this is really easy, or I’m a complete fool. I still don’t get it. Everytime I start to put in numbers, the number shows up in an unrelated 3x3 square on the other side of the puzzle. What is that about? > > How do I play this game? What do you mean the number “shows up” in an unrelated 3x3 square? The board should come with a certain number of pre-filled squares and no other numbers should “show up” during play except for the ones you fill in yourself. As for how to play, you simply have to make sure that: 1. Every row contains the numbers 1-9 2. Every column contains the numbers 1-9 3. Every 3x3 square contains the numbers 1-9 For more info, check out the [Wikipedia article](http://en.wikipedia.org/wiki/Sudoku) or [play a game online](http://www.websudoku.com/). ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [March 18, 2006, 8:35am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883/4 "2006-03-18T08:35:46Z")
Well, you have to make sure each digit appears EXACTLY once in each row/column/box. So let’s say a row has 3 blank squares, and one of the missing numbers is 5. You can’t just slap a 5 down in any of those, because it might cause a column or box to end up having two 5’s, which is not allowed. Some of them are certainly easy, but most places that you find them will have difficulty ratings of some kind, so you can work your way up. ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [March 18, 2006, 8:50am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883/5 "2006-03-18T08:50:55Z")
> [@TJdude825](#): > > Well, you have to make sure each digit appears EXACTLY once in each row/column/box. So let’s say a row has 3 blank squares, and one of the missing numbers is 5. You can’t just slap a 5 down in any of those, because it might cause a column or box to end up having two 5’s, which is not allowed. Some of them are certainly easy, but most places that you find them will have difficulty ratings of some kind, so you can work your way up. Oh, yes. For the hard ones, the process of elimination leaves blank spaces with 2,3, or more possible solutions and no definite answers; you have to go eenie-meenie-miney-moe every other space and end up with repeating digits. :mad: ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [March 18, 2006, 9:33am UTC](https://boards.straightdope.com/t/how-is-sudoku-played-exactly/348883/6 "2006-03-18T09:33:40Z")
The majority of sudoku only ever have one correct solution, and there _is_ a way of getting it, even if you have to worry away at it for hours. However, there are occasional mistakes made, such as [here](http://www.sudoku.org.uk/blunder.htm)