What is the best way to solve a Sudoku puzzle?
Starting with the 9’s, and working my way down, I first determine whether there are any obvious placements. If I can narrow it down to 2 squares in a given box, I put my number, in very small print, in the lower left hand corner of both of the squares in that box. If one square contains, for instance, a small 3 and a small 6, and another square in that same box also contains a small 3 and a small 6, I know that one of those boxes contains a 3, and one contains a 6. This is so obvious as to be almost silly, but it can give me clues for other placements. When the puzzle is partially solved, I will try looking at the column or row that is the closest to completion. If it still needs a 7, and all but one of the empty squares are in boxes that already contain 7’s, I know where to put my 7. These are a few of my techniques. When you fail to make progress with one, switch to another, and come up with some of your own.
