# Why are sudoku puzzles symmetric? **URL:** \ **Category:** Factual Questions\ **Created:** [September 15, 2006, 5:23am UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806 "2006-09-15T05:23:58Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![oliverlangan](https://avatars.discourse-cdn.com/v4/letter/o/839c29/32.png) [@oliverlangan](https://boards.straightdope.com/u/oliverlangan)\ **Post date:** [September 15, 2006, 5:23am UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/1 "2006-09-15T05:23:58Z")
I do the sudoku puzzle in the paper every day (and the ‘monster’ hexidecimal version on weekends). I noticed that they are always rotationally symmetric along a single axis. Come to think of it, so are crossword puzzles. Is there a mathematical/logical reason for this, or is it just a convention? ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [September 15, 2006, 6:49am UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/2 "2006-09-15T06:49:26Z")
[Cecil explains why crossword puzzles are symetric](http://www.straightdope.com/classics/a2_174b.html) > [@](#): > > Crossword puzzles are symmetrical mainly because (1) symmetrical puzzles appeal to their authors’ neurotic love of order (have you ever talked to a crossword puzzle editor?), and (2) the word arrays that crossword puzzles are based on have always been symmetrical, dating back to ancient times, when they were thought to have mystical significance. BTW, this seems to be an anglo-saxon tradition - in Germany, neither all crossword puzzles nor the sudokus are regularly symetrical. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [September 15, 2006, 6:53am UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/3 "2006-09-15T06:53:48Z")
Duh. I meant “anglo-american” tradition, not anglo-saxon. :smack: ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [September 15, 2006, 2:26pm UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/4 "2006-09-15T14:26:56Z")
I’m not sure what you mean by a sudoku being symetric. Do you mean that if there’s a 4 in the top right there will also be a 4 in the bottom left? I’ve never seen that. Do you mean that the grid is the same shape whichever way you turn it? Well, of course. What else could it be? You have to fit the same symbols into each column and row. I’m having trouble picturing a sudoku that has 10 columns and 7 rows. How could that work? ---
**Author:** ![oliverlangan](https://avatars.discourse-cdn.com/v4/letter/o/839c29/32.png) [@oliverlangan](https://boards.straightdope.com/u/oliverlangan)\ **Post date:** [September 15, 2006, 3:05pm UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/5 "2006-09-15T15:05:19Z")
[QUOTE=Peter Morris] I’m not sure what you mean by a sudoku being symetric. Do you mean that if there’s a 4 in the top right there will also be a 4 in the bottom left? I’ve never seen that. [/QUOTE] By symmetrical, I mean that the spaces that are blank vs. those that are filled are symmetrical, but not the actual numbers filled in. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [September 15, 2006, 3:42pm UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/6 "2006-09-15T15:42:06Z")
Ah, I see what you mean. No, the sudoku in the paper I have aren’t symmetrical. There’s no mathematical need for them to be. It’s probably just a gimmick in your paper. ---
**Author:** ![twickster](https://avatars.discourse-cdn.com/v4/letter/t/ec9cab/32.png) [@twickster](https://boards.straightdope.com/u/twickster)\ **Post date:** [September 15, 2006, 3:42pm UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/7 "2006-09-15T15:42:26Z")
Sudoku symmetry is just another convention – it makes the puzzle look nice on the page. twicks, who observed the first flush of sudokumania before leaving the puzzle biz. ---
**Author:** ![davenportavenger](https://avatars.discourse-cdn.com/v4/letter/d/5f8ce5/32.png) [@davenportavenger](https://boards.straightdope.com/u/davenportavenger)\ **Post date:** [September 15, 2006, 4:14pm UTC](https://boards.straightdope.com/t/why-are-sudoku-puzzles-symmetric/372806/8 "2006-09-15T16:14:05Z")
The sudokus in my sudoku book aren’t symmetrical in the way you describe. As for crossword puzzles, I think it is just because it looks nice. We did crossword puzzles with our vocabulary words in them in elementary school and they weren’t symmetrical. I remember thinking how weird that was.