Once you know the methods, solving Sudoku would be easy for you. Take this grid for example:
We can first check. Remember that in every 3*3 block the numbers 1-9 can only appear ONCE. In this case, the block here:
We can fill in the remaining number (7).
The rule also applies the same to every column and every row.
After this, we can use the method of scanning. Since every 3*3 block has 9 numbers that never repeats and when these blocks are put together, those numbers would also not be repeated. Thus, a pattern could be seen. For example, the no. 6 was seen in the first block in the third row, middle column, then, in the next block, 6 canˇ¦t be in the third row, nor the middle column. If the Sudoku grid you are having consists of two of the same number in three consecutive rows/columns, you can easily find out where the third same number should be put. Look at the example:
These methods can help you get most of the grids in the Sudoku. There would be one more way that you can use. Take this grid as an example:
On the grid, we can see that the arrow-pointed grids must be either 2,4 or 5. To solve this, we can use pencil marking.
Using the information we have, put the possible numbers, or ˇ§pencilmarksˇ¨ on the top left corner of the grid. For the first column, because of having 5 already, cross out the possibility of 5 in the three numbers and put 2 and 4 on the top left corner. For the second column, pencilmark 2. For the third column, pencilmark 2 and 5
Here are the combined pencilmarks. Compare them.
For the grid in the second column, 2 is the only possibility, so fill the grid with 2
Cross out the other possibilities of 2.
Only one possibility is left for each grid, so fill those grids in with that number.