Sudoku Solving Techniques


Sudoku became a very popular puzzle game primarily because it provides an engaging challenge to both, new beginner players as well as seasoned Sudoku puzzle solvers. The approach to solve the Sudoku puzzle might be different, but it all comprising of finding the one unique solution that will fit into the grid. Each Sudoku puzzle has only one unique solution.


You cannot solve a Sudoku puzzle through guesswork. Therefore, your first few times playing Sudoku can be somewhat intimidating and challenging.


Most of the time, newbies guess the easy allocation numbers, then keep perfecting their problem-solving skills as they understand how the game works.With the help of a few tips and some logic, you won’t need to struggle to solve a Sudoku puzzle. Here are some of the most straightforward Sudoku solving  techniques you can use to solve many Sudoku puzzle.


One Direction Scanning and Missing Single numbers 

One direction scanning’s primary strategy is to study the puzzle and identify the missing digits in each row. Simply chose a number and see where it fit within the row and column and if there is one possibility in the third row or column or within a 3 x 3 block. This strategy is not limited to rows alone; you can equally look through the columns, spot the missing numbers and fix them in the correct slots.


For Example



If we scan row 3 and row 2, we can see the 9 (marked in yellow) in cell R3C2 and R2C7, now if we scan row 1, there is only one possibility for the number 9 in R1C5 (marked in yellow)


Missing Singles 

A missing single is an individual digit missing in a column or row. Finding an absent single is simple since you only have to look at the available numbers, figure out the missing one, and put it in its rightful spot. 


Two-Direction Elimination 

In every Sudoku puzzle, each row and column has to have all numbers between 1-9. Scanning in two directions (looking at both rows and columns) allows you to discover which number is missing in a row or/and a column.


This technique is similar to the one-direction scanning; only that in this case, you have to scan columns and rows simultaneously..

two directional scanning1

In this example we look at row 1 and row 2 with number 1. We see 2 possible cells to fill the number 1, R3C7 and R3C9, but since there is a 1 in R4C6, the only possibility for the digit one is in cell R3C9 (marked Green)



Eliminating a Digit from Columns, Rows, and Blocks 

This strategy is similar to the single candidate search, only that in this scenario, you get rid of numbers that you have already used in the respective spaces. Once you determine which numbers are in the cells, you will discover those that are missing. From this point on, you have to use your pencil and some thinking to figure out which number goes where.


Unique Numbers 

Another method to solve a Sudoku puzzle is to find unique numbers. These are digits that are missing in a 3 x 3 block. We know that each block should have one integer between 1 to 9. So, divide the puzzle into 3 x 3 blocks.( we have 9 3×3 blocks)) Check which common digits are available within each 3 x 3 block and see if this will lead to place this number in another 3 x 3 block that does not have it..

This will become clearer with the example below.

You will discover that particular digits are common to a majority of the blocks. For instance, you’ll see that most of the 3 x 3 blocks have the number 2 in them. However, 3 x 3 blocks 5 and block 8 (marked in blue) do not have the number 2 in them. Therefore, you will only have to find the blocks that do not have this number and find a befitting cell for them. Once you solve one box, it becomes easier to fill in other blanks in the other 3 x 3 boxes using this strategy. 


In this case, you have to find a spot for this number (digit 2) in both boxes. Rows 6 and 7 do not have number 2, making them great places to look into. Now R6C6 (marked in yellow) and R7C4 (marked in green) make the best choices since there is no clashing number 2 in correspondent rows or columns. Now it is easy to figure that in 3 x 3 box 5 the best place to put a 2 is in cell R6C6 Because you cannot put a 2 in row 5 ( because of the 2 in R5C1) and in row 4 because of the 2 in R4C8 so the only choice is R5C5 or R5C6 out that the number 2 but column 5 has already a 2 in R3C5 therefore the ONLY place for the number 2 is in R6C6 ( marked in green) From there, it is easily figured that 2 will also go into 3×3 box 8 in cell R7C4 as it cannot be in any other cell in 3 x 3 box 8



Pencil Marking 

Until this point, the Scanning and Elimination techniques above do not involve multiple candidates per cell. As you start to solve more challenging Sudoku puzzles, you will find that some cells can hold 2, 3 or more possible candidates. Pencil marking is the exercise of writing down little pencil marking of these number candidates in a cell in order to keep track of all the remaining possibilities. Most puzzle solvers prefer to scribble small numbers at the corner of a cell, making it easier to analyze where each probable number should go, thereby eliminating the odd ones. The idea is to help you recognize certain patterns and help to eliminate some candidates.


Pencil marking may not be possible in all scenarios, especially if you play on your phone or tablet or online and these provisions are not available. In such cases, you can draw the Sudoku grid on paper, solve it, and then write down the grid’s answers.



Naked Subsets

Naked subsets occur when two or more number candidates for a cell in one row, or one column, or one 3×3 box containing few different numbers candidates, then those other cells with the same number candidate can be eliminated from the other cells in the row or column or 3×3 box. 


Let’s look at an example to make it clear


.In this example, Cells R8C3 and R8C4 are both in the same row (row 8) and have both only candidates 3 and 9 left to occupy these cells.( highlighted in blue). Therefore if these 2 cells can have the number 3 or the number 9 It stands to reason that cell R8C2 CANNOT be 3 and therefore the number 3 can be eliminated leaving there number 7 (cell highlighted in yellow)\.


There are three types of subsets which are:

  • Naked pairs – When you are searching for only
    two numbers
  • Naked triples – A scenario where you are
    looking for three candidates
  • Naked quads – Happens when four digits are
    missing from a block all with the same logic

Practice to Perfect Your Skills

 What makes good Sudoku solvers? The answer is – Practice! The more one play, the more familiar one become with the different possibilities and the more proficient one become at solving the puzzle. Start

by solving the easy and simpler grids, then builds up to harder ones as your problem-solving skills improve. To learn more challenging Sudoku solving tips, try this article


Another important thing is that a Sudoku puzzle can be solved between 2 or more people as well. There will be one person responsible to put the suggestions in the grid, but this is a great game to play with your significant other or with friends.



 Sudoku is a game that requires wit, skill and patience. You have to understand the metrics of each puzzle so that they can guide your decision-making process. If you’re playing a virtual game, you can use available tools to pencil-mark the prospective answers. However, if you’re solving one of those Sudoku puzzles in your daily newspaper, then the traditional pen and eraser will work just fine.


You can play free online Sudoku on our site by clicking here where you can play online or you can print the puzzle and solve it with pencil and eraser. It provide you with a chice between 3 difficulty levels – Easy, Meedium and Hard. 


If you interested in our magnificent book with over 1100+ Sudoku puzzles from easy to Super hard,   

Click Here


You can use each of the Sudoku’s solving tips above to solve a puzzle, yet by using a combination of all of these techniques makes the journey easier, and helping you finish up the puzzle faster. Remember, this game requires practice and patience so, do not sweat it if you cannot complete a puzzle in a short span of time or in one sitting. Remember – Practice make it perfect.