There are different kind of techniques to solve the different levels of Sudoku puzzles. The Sudoku Tutorial shown on this page will guide you through all different levels of Sudoku’s from Easy, Hard to Killer Sudoku’s. All you need are four hint and tips and they are explained on this page and will help you solve all your Sudoku puzzles.
Each square (3×3), row and column can contain each number only once. So check for each 3 rows and columns if there is only one place where a number fits. In Example 1 it is clear that in the left square number one can only be placed in the bottom row on the left. The best is to check this for each number first per row and then by column.
In example 2 it is a little bit more difficult. The number 8 can in the left square only be placed in the middle row. This means that in the middle square number 8 can only be placed in the bottom row.
Example three is my favorite and will help sometimes when you are stucked. Each row and column can contain each number from 1 to 9 only once. If we look at the position with the questionmark you will see that all numbers are coverd in the same row or column except number 2.
Example 4 shows you place a number even if it is not used. Number 8 and number 9 must be in the top row. This means that number 3 can not be placed in the top row and so it must be place in the row in the middle. There is no other way to place number 3 even if you don’t know the positions of number 8 and 9.