Stay far away from SuDoku. It’s a Japanese number puzzle. You’re given a board like this one:

And you have to fill in the blanks. Each row, column, and marked 3×3 square must contain the numbers 1-9 exactly once.
It sounds really simple. And it is, for the first few squares.
It’s the last few squares that bite you, and then you have to go back and change things, or start over.
Why should you stay away? Because this will eat your time. I picked up one of these today, and it took me over two hours to finish.
Actually, if I had to do another one, it’d probably be a lot easier. The trick to this game comes in the extended entry.
OK, so here’s what I eventually did: I made up an Excel spreadsheet with all the marked squares typed in. In the unmarked squares, I typed in the number 123456789. Then I printed out the resulting sheet. Then I crossed out all the options that were unavailable in each square. For example, in the square on the third row of the left-hand column in the example graphic, the number would have looked like 123456789. This square could only contain the number 1 or the number 2.
I did this for every square. In the board that I was playing, there were two instances where all but one number was eliminated. In the example graphic, the bottom empty square of the right hand column is an example: Only the number 4 fits in there.
I would then write that number in the corresponding square on my board and cross out that number on my worksheet in all of the squares that that square affected: crossing out the 4’s in all of the squares in that column, row, and 3×3 square. And so and so forth until eventually the puzzle is complete.
In case you’re wondering, the solution to this particular board is located here.
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