Ive just come back from holiday where I tried to pass the time by doing sudoku. After the first obvious squares I came to a dead halt! Anyone got any tips on how to do these? i suspect that there is a logic that if you cant get it you never will. And for those that can get it there is no challenge.
nothing to do with numbers - they could be letters or squiggles or anything. One of the most useful rules is this: if two squares in a line/column/box could both have only the same two numbers - say 2 and 5 - then 2 and 5 can't appear anywhere else in the line/column/box, so you can eliminate them from the possibilities. (Same for three numbers that only appear in three squares, etc).
PS: there's still a challenge. I know most of the rules and it can still take an hour or more. It depends on how much time you want to spend on puzzles, but they're useful on trains, toilets etc.