Simplifying Sudoku

I got hooked on Sudoku a couple years ago when it boomeranged back into the US from Japan. This little nine by nine grid puzzle that looks like a crossword actually originated in Indianapolis where architect Howard Garns designed it in 1979. It was published under the name Number Place by Dell Magazines but the game didn't flourish until it was released in Japan by publisher Nikoli in 1986. It had been renamed Sudoku, which means "single number". That pretty much describes the game. When the London Times published a Sudoku puzzle in November 2004, the Western craze began.

The beauty of Sudoku is that it is not based on math; it is based on logic. Most puzzles feature the numerals one through nine and the goal is to fill each row, vertically or horizontally with those numbers using each number only once. Additionally, each three by three section will be completed the same way so that the whole thing lines up in three different directions. The numbers themselves are irrelevant - they could be nine different symbols or pictures and the game would be the same. In fact, Viz magazine published a version of the game using nine photos of characters from the television series Dr. Who. So don't let the numbers scare you. They're only numbers.

Now for strategy. You can find lots of how-to for playing Sudoku on the web. I googled and printed out all sorts of tips to try to understand things like "hidden singles" and "naked pairs" (hmmm, sounds a bit more exciting now, doesn't it!) but in the end, I realized it was best for me to just let my mind tune into the game and be intuitive. That didn't happen right away, and I did some complicated stuff that almost ruined the game for me, so let me walk you through that process.

It made sense to me that you should first scan each square and lightly pencil in each number that was a possibility. Then, as you solve more squares, you erase or cross out the eliminated numbers. That seems simple enough, but this took a LOT of time and it was a huge mess. The squares weren't always big enough for all that tabulating. Plus, it was work to list all those possibilities before you even got to play the game! Still, I persisted.

I decided that there must be a template that would accommodate this method and I found one here. Yayyyy! I worked up a few versions of the template: one to a page, two to a page, etc, and printed them out. I went to DailySudoku.com, my favorite source of free puzzles, and filled out a stack of templates. I usually note the date on the puzzle so that if I run into trouble, I can go back to the website to see the solution and see where I went wrong. Gotta have closure, you know.

Since my daughter Ellyn also likes to play Sudoku, I gave her a stack of games on my new template. She hated it. I was surprised, but she said that it was too much clutter on the page and besides, she didn't work the puzzle by that method. I agreed that it was a lot of clutter but I couldn't see how else to approach the game. What other way was there to play? Ellyn got a gleam in her eye at the prospect of straightening me out - I recognized that look from having survived three teenagers. It was a scary moment of deja-vu, but what Ellyn showed me made Sudoku simple and fun.

Ellyn and I sat side by side on the couch so she could demonstrate. Rather than going square by square for ALL possibilities, she quickly scanned each box and each row. Naturally, if you spot a square where there is only one possibility, you fill that one in. (I actually circle these as a signal to myself that these are non-negotiable and are correct.) But the key is to only pencil in possibilities if the number will only fit in two places in that row. If it looks like it would fit in three or more squares in any given row, move on and scan for the next number. You will skip through a lot of numbers this way, but you are gradually narrowing the field and only entering numbers into squares where they will really go. It sounds simple, but it is quite profound. Rather than looking for every possibility for every square, which you don't even need to know, you are saving yourself a lot of work while filling in the most obvious squares of the puzzle.

After going through each 3x3 square and each vertical and horizontal row several times, you will have completed a lot of the puzzle. You might be tempted to pencil in a number for a third time in a given row. Don't. It really doesn't help solve the puzzle and you just need to be vigilant as to what you are missing. When I get stuck at this point I do have one more strategy. I sometimes look at a single square and determine what it CANNOT be. That sometimes takes me down to only two - or even one - possibilities.

I can't tell you how this simple method has improved my Sudoku game and made it much more enjoyable. Now I start right out playing the game without trying overly hard to figure out everything upfront. If you are more mathematical than I am and enjoy going through lots of theories while you solve the puzzle, then by all means continue to do so! This is just my own way of making Sudoku a pleasant pastime that isn't too easy and no harder than it needs to be.

By the way - don't forget the kids! You can start them on logic puzzles in grade school. Check out Kid's Sudoku and help them learn to think!

And did I mention that I have a very smart daughter?