Sun Times Sudoku

[sohcahtoa]

Would appreciate help on how to finish Sudoku puzzle after I have tried all possible routes.

[SYRAC]

Presume you've checked every cube and every line. If a number will only go in any 2 sections of a cube I use a pencil to write it in. Often this helps. Failing all else I choose a cube where 2 sections have the same two numbers as a possibility, ie either, for example, only a 3 or 4 will go in either of the sections. I choose one of those numbers in one square and circle it. This means I can immediately fill in the other square in that cube again circling the number. From then on I circle any number obtained and soon know if I'm wrong as I get to an impossible situation. If this happens I go back to my first circled guest (eg the 3 or 4) and start again knowing I must now be right with my choice. Hope this makes sense to you, good luck, I love Sudoku.

[sohcahtoa]

I understood that there is a logical method of solving Sodoku, rather than trying out a choice to see if it works.

[SYRAC]

I always thought that and most of them are, but then I bought a book of these horrible Sudoku and was absolutely stuck, I spent days on one. Then I read the introduction bit in the book to look for help and it said to do what I've tried to explain above.

[sohcahtoa]

Thanks - will try again.

[SYRAC]

Mind one thing I forgot to say was the book suggested you do what I tried to explain in your head - I tried. No way, I got in a right mess so out came the pencil. There is a sort of logic to the method insofar that you say if x goes here and y goes there then z would go there, and so on. If I don't get an impossibility within about 10 "goes" I'll usually go back and start with the other alternative. That usually proves wrong before long so I know my first choice was correct.