Answer:
To win Sudoku you can have each number in 1-9 once in every medium box (square) with no repeated numbers , and also 1-9 in each row and column. with no repeated numbers.
note:
Youcan win easily if you are good at math because all you have to do is only calculate.
Since there are 9 solutions in each small square, then the solutions are limited; which is either 1, 2 , 3 ,4 ,5 ,6 ,7 ,8 ,9.
You can take out all the numbers that are in the same line with our unknown square. You must do this for both row and column (horizontal and vertical).
After that, you must also take out each and every number you have in that medium box (square) to limit the possible answers because you can't have two of the same numbers in the same column or row or the medium square (box).
Now, if you looked at your total (final answers) and the remaining numbers you will have either one, two, or maybe three possible solutions for that little square.
Always chose Sudoku with a lot of numbers because it is easier to solve and good look with your Sudoku puzzle.