tips and tricks for beginners and experienced players
HOW TO PLAY SUDOKU
The objective is to fill a 9×9 grid so that each column, each row, and each of the nine 3×3 boxes (also called blocks or regions) contain the digits 1 to 9.
A cell is the smallest block in the game. A row, column and region consists of 9 cells and the whole game consists of 81 cells. A region usually has thicker lines dividing it. This simply makes it easier to play the game
THE BASICS OF SCANNING
The most basic strategy to find missing numbers is scanning and it consists of either cross-hatching or counting.
Crosshatching: You scan rows and columns to eliminate where a specific number can be in a given region. As you can see there is only one legal place left for the 9 (marked teal)
Counting: In counting you simply count all the different numbers that’s in a row, column and region that connects to one cell. If there is just one number missing then that’s what should be in the cell. Take a look at the second image and see if you can figure out the missing number in the green cell. The correct answer is: 6
PENCIL IN CANDIDATES
Are you stuck? It’s time to take notes and pencil in all the possible candidates for the remaining cells.
The example to the left shows all possible candidates for the partially solved puzzle.
You can quickly see that there are several “naked”single numbers standing alone. The naked numbers are 1, 2, 5, 6, 8, and 9.
When you fill in the naked sqaures you can eliminate those numbers from your notations. Leaving you with several more ‘naked’ numbers through process of elimination.