aapje89 posted on Mar 7 2007 at 07:19 AM said:
Well, teach me then, do you have a link to a page who explains how to do it maybe?
Unfortunately no, I'm not aware of any sites that teach you how to do it all in your head, they seem to all start off by teaching you the note-taking method, probably because it's an easy way to teach Sudoku.
I start off by working the rows from top to bottom. I look to see if there's already a 1 on the first row. If not then I look to see where a 1 could be placed. If I find there is more than one to put the 1 then I immediately look for where the 2 could be placed. I carry on till I've got up to 9 and then I move to the next line down.
Once I've reached the bottom then I work the columns, left to right. Same method.
Once I've finished the columns then I look at each 3 x 3 square, working top to bottom, left to right.
Once I've done all of that then I start again with the rows.
Most times this process works, but occassionally I get to the stage where I've done a complete pass through the grid (rows, columns, squares) without figuring out a single number. At that point I revert to writing notes, i.e. working out all of the possible numbers that can go in each square. Then I use the normal methods of looking for 2 doubles or 3 tripples.
Sorry if this sounds confusing, it's easier to show someone than it is to explain it!