In this advanced Sudoku strategy tips tutorial post I’ll be doing another example of where you can use the advanced X wing method to help you solve very hard Sudoku puzzles. You can also visit my previous post for more X wing column variation tutorials with examples.

Contents: Starting Sudoku Grid | Stuck on a Hard Sudoku? | Using the X wing Sudoku Strategy | More Advanced Sudoku Strategy Tips & Tutorials

Starting Sudoku Grid
In diagram 1 you will see the blank Sudoku grid used in this X wing tutorial.

Diagram 1 - X Wing Advanced Strategy

Stuck on a Hard Sudoku?

Diagram 2 - Advanced Sudoku strategy tips

Diagram 2 shows the cells I have managed to fill in the Sudoku grid – colored green. And also in diagram 2, you can see the cells where I am unable to find a definitive answer or number for the cell and so have noted the possible numbers that could be in the cells. If you unsure, how to play Sudoku, you may want to check out my previous post: Step by Step How to Solve Sudoku – Sudoku Tips and Rules.

However now that I have filled in all the cells of the grid in this very hard Sudoku example I am unable to continue the Sudoku puzzle using the simple method of deduction and elimination, so I must look for possible opportunities to use the advanced Sudoku strategy tricks. In this case, I’ll be using the X wing column variation technique.

Using the X wing Sudoku Strategy

Diagram 3 - X wing Column variation

Diagram 3, I have highlighted in yellow a possible opportunity of using the Xwing strategy. To check that the rules for the X wing technique can be applied, in this case to these 4 yellow cells, I must make sure that the number that I am going to apply the X wing method to, only appears in these 4 cells in each row. So for this example, I can see that the number 7, only appears in the 4 cells of rows 3 and 4. In other words, they make the 4 corners of a rectangle. So they do indeed make a case to use the X wing strategy. Remember that by applying the Sudoku rules, the 7 can only appear in one of the highlighted cells in rows 3 and 4. Similarly, the 7 can only be in one of the yellow cells in columns 3 and 9. And so, the 7 can only be in the opposite corners of this rectangle, hence making an X, i.e. an X wing formation.

Now that we have determined that this is an X wing, we know that there can be no other 7′s in the same columns i.e. columns 3 and 9 (the blue cells). So I can now remove the 7′s from my notations in these columns. As a result, this has immediately helped me to solve 3 more cells. First, the blue cell with the ’76′ notation can now be resolved to be 6. Similarly the blue cell with ’79′ notation can now be determined to be 9. Subsequently, the blue cell with the ’678′ notation, has to be ’8′.  So using the X wing technique has enabled me to solve more cells, and should now help me move on with solving this Sudoku puzzle!

More Advanced Sudoku Tutorials
For more advanced Sudoku strategy tips and tricks with video tutorials and examples:

Advanced Sudoku Strategy Tips and Tricks – X Wing Tutorial 2

In this advanced Sudoku strategy tips and tricks tutorial is an example of how to use the X Wing technique to solve very hard Sudoku puzzles. If you would like a tutorial on how to start a Sudoku and the Sudoku basic rules, please check out my previous post: Step by Step How to Solve Sudoku – Sudoku Tips and Rules. Also if you would like to know what the X wing advanced Sudoku strategy is, you may also want to check out my previous post: An Introduction to the X Wing Advanced Sudoku Strategy. However, in this Sudoku tutorial you will see an example of a Sudoku puzzle where you can use the X wing strategy, and this example uses the column variation of the X wing technique.

Diagram 1 shows the starting ‘blank’ Sudoku puzzle.

Diagram1 - X Wing Column Sudoku Strategy

Diagram 2 now shows where I have managed to fill in cells by a process of elimination, and also my ‘pencilled’ notations, where I have been unable to whittle the answer down to a definitive number, and so shows a number of possible candidates. If you are unsure how to play Sudoku, I recommend going back to my post Step by Step How to Solve Sudoku – Sudoku Tips and Rules to learn the basics.

Now I am unable to progress further with this puzzle, so I am going to see if I can use one of the advanced Sudoku strategy tricks to be able to continue with the puzzle. In this case, I will try the X Wing column variation. The X Wing method is one of a number of handy Sudoku tricks that you can use to solve very hard Sudoku puzzles, when you get stuck, just like the example in diagram 2. I hope to cover more advanced Sudoku techniques in future posts.

Diagram2 - X Wing Sudoku Tricks

If you recall from my previous post An Introduction to the X Wing Advanced Sudoku Strategy the X Wing strategy can be used when you find that you have the same possible candidate in 4 corners of a rectangle. The 4 cells in this example are shown by the highlighted yellow cells in diagram 2.

You will see that the number 8 features as a candidate in all of these 4 highlighted cells. To double check that this is indeed a situation that you can use the X wing column variation, you must also check that the possible candidate, which is 8 in this case, does not occur anywhere else in the rows that make up this rectangle (i.e. row 5 and row 8).

So to recap, you are looking at your ‘pencilled’ notations for an occurrence of one possible candidate in 4 cells that will make the corners of a rectangle, and make sure that this same number does not occur anywhere else in the rows of the rectangle, except in these 4 cells. If you find this, then you can apply the X Wing column variation technique.

Applying Sudoku Tricks: X Wing Column Variation
Now applying the basic Sudoku rules and the X wing method, we know that the 8 can only occur in opposite corners of this rectangle. So, the 8 can only occur in the following cell pairs:
a. in cell row 5/column 1 and cell row 8/column 9 OR b. in cell row5/column 9 and cell row 8/column 1

In other words the 8 can only appear in opposite corners of the rectangle, and you will see this makes an X, which is why this Sudoku strategy is called the X wing.

Now, knowing that the 8 will be in one of the pairs of highlighted cells, we can now say for sure that the 8 cannot appear in any other cells of the columns that make up the rectangle. By finding the X wing column variation formation, we have narrowed down the occurrence of the 8 to the highlighted cells of columns 1 and 9. As such we can now look at the other notes we have made for these columns and remove the 8′s.

Diagram3 - Advanced Sudoku Strategy

In diagram 3, you will see that the 8′s have been crossed out with blue pen marks. This application of one of the advanced Sudoku tricks has helped us to continue with the Sudoku that we would otherwise have been stuck on, because as you can see we have solved another cell (row 2/column2) and we now know the answer is 2. This opens up the puzzle again so we can move on and continue to solve it.

So this Sudoku tutorial shows that even when you are stuck, you can see how to solve very difficult Sudoku by looking for situations when you can apply advanced Sudoku strategy tricks. Don’t be put off by the length of this post, it does take a lot of words to explain it, but in actual fact this is a very quick method to use once you practise and become familiar with the technique.

For more advanced Sudoku strategy tips and tricks with video tutorials and examples:

Advanced Sudoku Strategy Tips and Tricks – X Wing Tutorial

Whether you are an experienced Sudoku player and wanting to take your addiction of Sudoku to the next level or if you’re a complete newbie that wants to learn Sudoku but just not sure to how to start a Sudoku puzzle. You may be interested in this complete and easy to use guide on how to solve Sudoku using video lessons. This step by step Sudoku guide shows you in video format, all the aspects of learning and solving Sudoku, from the basics with easy to learn methods, the rules and terminology to the more advanced Sudoku strategy and techniques with Sudoku tips and tricks used by experts.

It can be difficult to grasp how to solve Sudoku just by reading how to do it, so if you are more used to learning things visually, then following these video tutorials may, not only be easier to learn Sudoku but will also be simpler to show you rather than write out explanations, which can be quite lengthy when it comes to the more difficult, hard to beat Sudoku puzzles. As the saying goes ‘a picture paints a thousand words’ and with a video tutorial you can see exactly each step to solving a Sudoku puzzle.

For Sudoku Beginners -Solving Easy Puzzles
Included in these videos, starts from the basics including Sudoku rules, how to begin a puzzle, the concept behind Sudoku, scanning and elimination.

For intermediate Sudoku techniques
Once you have perfected the Sudoku basics, there is whole load more of strategies and techniques. Intermediary strategy methods such as pairs, triplets and quadruplets and how to spot them.

For the advanced Sudoku solver
These videos show you how to beat hard puzzles using advanced techniques like X wing, Swordfish, XYZ wing. These tutorials progress through the Sudoku methods incrementally, so that it is easy to grasp more advanced strategies without getting lost or overwhelmed!

For the toughest most difficult Sudoku strategies
From linked pairs, grid coloring and bilocation graphs. While many Sudoku books can be difficult to follow. Watching these videos, for such hard strategy tricks will make learning them a breeze!

Learning Sudoku in 30 Video Lessons

• Lessons 1 to 7 include Sudoku basics, Sudoku rules, concepts and terms. Plus single choice, candidates, scanning and elimination.
• Lessons 8 to 14 include learning about finding naked pairs, naked triplets, naked quadruplets, hidden pairs and hidden triplets.
• Lessons 15 to 22 include advanced Sudoku strategy methods like X wing column and row variations, Swordfish variations, Jellyfish, XY wing, XYZ wing and WXYZ wing.
• Lessons 23 to 30 include very advanced techniques such as linked pairs, grid coloring, bilocation graphs, Nishio guessing and backtracking.

So whether you have been struggling to learn how to Sudoku or you are stuck on a killer Sudoku, then this suite of 30 step by step lessons in video format will help you. With clear, concise, expert instructions that cater for any level of Sudoku player, from beginner to seasoned pro.

For more details, click on the link below to discover how you can enhance your Sudoku skills whatever your current level of expertise:

Learn How to Sudoku with Simple Step by Step Video Tutorials

Learn How to Solve Sudoku with Step by Step Sudoku Video Lessons

Following on from my previous post on advanced Sudoku tips and tricks, in which I introduced the X wing strategy. This post is an introduction to an even more difficult method. In fact it is one of the most complex Sudoku strategies, and that is the Swordfish technique. Please note, this is just an overview, for now of this technique. A more detailed tutorial will follow in due course, once I have outlined all the different Sudoku strategy methods.

Contents: Introduction to Swordfish | Swordfish Row Variation | Swordfish Column Variation | Swordfish Advanced Tips & Tricks

Introduction to Swordfish Sudoku
In effect, the Swordfish method is the same as X wing technique but where the X wing requires you to spot patterns over two rows and columns; the Swordfish uses three rows and columns.

As with the X wing there are 2 variations to this Swordfish strategy – the row and column variation. In order to help you spot if any of these strategies can be used, it is easier if you mark your possible candidates with pencil notations in the grid.

The Swordfish row variation
For this scenario, you are looking for three rows where there are two or three possible cells for which a particular number can be put in. And, simultaneously, for all three rows these cells must lie in the same three columns.

sudoku swordfish row variation

The Swordfish column variation
For this scenario, you are looking for three columns where there are two or three possible cells for which a particular number can be put in. And, simultaneously, for all three columns these cells must lie in the same three rows.

sudoku swordfish column variation

Swordfish Sudoku Tips & Tricks
* To use the row variation of the Swordfish method, you are looking for where you can eliminate a particular number from all the other cells in the three columns.
* And vice versa for the column variation.
* As the Swordfish strategy is a difficult one to spot, you may find it easier to focus on one number at a time. And evaluate each number against your pencil notations, for each row and then each column, in turn.
* For more advanced Sudoku strategy tips, video tutorials and examples:

Advanced Sudoku Tips and Tricks – Swordfish Strategy

Once you have grasped the basic Sudoku rules and used the Sudoku strategy tips and tricks detailed in my previous easy tutorial posts you’ll see how easy it is to become quite familiar with the basic concept of Sudoku puzzles.
The previous posts shows you how to solve Sudoku using simple strategies and techniques. But as you become more adept at solving Sudoku, you’ll no doubt want to learn about more advanced Sudoku tips and strategies.

As explained in my previous posts, using pencil marks or notations to make a note of possible candidates is a great Sudoku trick to help you solve Sudoku puzzles by listing the values that could go into a particular cell.
But, these notations can also be used to apply many advanced techniques. By spotting patterns in your notations you can apply certain advanced Sudoku strategies. Whenever you solve a square, you must remove that number from the pencil marks in all other squares in the same row, column and block.

One example of an advanced Sudoku strategy is the X Wing.

The X Wing is in effect, an advanced method that uses the fact that in certain scenarios, there can only be 2 possible ways of inserting two numbers in a given set of four squares, which are the corner cells of a rectangle. Because this indicates a relationship between diagonally opposite corners it forms an ‘x’.

To illustrate this, here are 2 diagrams showing the X Wing strategy, with 2 variations – column and row X Wing.

sudoku xwing row variation

sudoku xwing column variation

There are many more advanced Sudoku strategy tricks and I will be introducing them over in the next few posts, before going into detail with a tutorial of each Sudoku strategy.

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Advanced Sudoku Tips – An Intro to the X Wing Advanced Sudoku Strategy

This is the last part of the step by step easy Sudoku tutorial using the easy Sudoku puzzle example. And this post is mainly diagrams of the interim stages, towards the solution. As I have already described the method, rules and tips that you should use for solving this easy Sudoku puzzle example, in the previous 2 posts.
Diagram 10 below: In the bottom row of the top right hand box, you’ll see that of the ’1,3′ options, the 3 cant go in any other of the empty cells of the row (row 3), except where I have noted ’1,3′ so this has to be 3, leaving 1 to be placed in the top middle of this box. Making the top right hand box also complete.

Diagram 10

In row 3, which is missing 1, 5 and 8, because there is a 1 already in the middle box, means only ’5,8′ can go in this row.

Diagram 11: in Column 5, 1st cell, go through which numbers are missing and see if can at least make notation to the possible entries. Column 5 is missing 2, 3 and 6. There is already a 2 in the box this column is in, so I have entered the notation ’3,6′ as shown in the diagram.

Diagram 11

Continue looking at the missing cells of this column 5. In the bottom middle box, there is already a 3 in it and a already a 6 in row 8 of this column, so this cell must be for the missing 2 and so leaves 6 to go in the bottom empty cell of this column.

Diagram 12: Continuing this Sudoku puzzle

Diagram 12

Diagram 13: And a few more entries along and should have something like this.

How to Sudoku Tips - Diagram 13

Diagram 14: And finally the complete solution to this easy Sudoku puzzle.

Diagram 14

How to Solve Sudoku – Easy Sudoku Tutorial part 3 of 3

This is part 2 and follows on from where I left off in the step by step how to solve an easy Sudoku tutorial of my previous post. The example I’m using is an easy Sudoku, just to show how to apply the Sudoku rules as described in my previous post. So this post shows interim stages with diagrams and descriptions of solving this Sudoku puzzle. You can pick any of these interim puzzles to practise doing Sudoku yourself. Just remember to apply the basic Sudoku rules as I described previously.

Diagram 7 shows the next step in this step by step tutorial. The bottom right-hand box is missing 2,5 and 4. As there is definitely a 4 in the last column, and the 4 can’t go in the top middle cell of the box, the 4 has to go in the bottom middle cell, as shown in diagram 7. And so the remaining unused numbers 2 and 5 are put in as notations in the remaining cells.

Diagram 7 in this Sudoku Tutorial

Diagram 8 shows the following new entries: top right hand box, bottom right cell notation of ’5,6′. By scanning the second row down, can see there is only one place the 4 can go now, as there is already a 4 in column 4 and 8 for this 2nd row. Then sticking with this 2nd row, there is only one place that the missing 6 can go, and leaves just one space for you to add the remaining missing 5 – and now this row is complete.

Diagram 8 Next Steps

Remembering the Sudoku tips of my previous post, i.e. you cannot have the same number duplicated in each row, column or box. So applying the Sudoku rules, now that you have just added this 5 in row 2 you can now knock out the 5 in the ’2,5′ notation in the top row of the bottom right box. Similarly you can now remove the other ’2,5′ notation, and change to 5. Now as you put in more entries you get more possibles to help you solve the Sudoku puzzle.

Diagram 9: change notation in top right box from ’5,6′ to 6. top right box top right hand corner is the only cell the missing 2 can go, the remaining missing numbers ’1,3′ are noted in the empty cells.

Diagram 9 Sudoku Tutorial

This Sudoku tutorial will be continued in my next post, but apply the Sudoku rules and tips and you can complete this Sudoku puzzle yourself in the meantime.
For the steps for how to start this particular easy Sudoku puzzle example, see my previous post.

Using Sudoku Rules in Step by Step Easy Sudoku Tutorial part 2 of 3

In the next series of posts I will show you some Sudoku strategy tips to solve easy Sudoku puzzle. I’ll be using an easy puzzle as an example and working through it in this series of Sudoku tutorials. Including step by step instructions and pictures at each stage showing you how to solve this Sudoku puzzle. This is a great starting point if you would like to learn how to solve Sudoku but don’t know where to start, as it incorporates the main Sudoku principles/rules that I detailed in my previous post.
I wanted to go over the basics first before moving onto the advanced Sudoku tutorials, as the same basic Sudoku rules apply.
In this post I am just going to show you how to start a Sudoku puzzle, step by step. When a written step by step description for solving Sudoku can be quite long, which is why I am splitting this into a number of smaller posts. But, and this is my first tip, with practise you can learn how to not only be quicker at solving the puzzles but also progress to more difficult ones as you get better. Sudoku is a game of logic and elimination and with practise you will see how much fun they are to do as well as a good way to give your brain a bit of exercise!

Diagram 1 shows a blank 9×9 Sudoku grid. This is an easy Sudoku, Sudoku range from easy, medium, hard, difficult and advanced. Basically the more numbers pre-filled in a Sudoku puzzle the easier they should be to solve.

Diagram 1 – Recap Sudoku Rules

By applying the Sudoku rules a. each column, row and box must have all the numbers 1 to 9 in them and b. you can only have one occurrence of the numbers 1 to 9 in each column, row and box, you begin to solve your Sudoku.

Sudoku tip: As a good starting point, begin by scanning the whole grid for rows, columns and boxes that have the most numbers already pre-filled.

Diagram 2 – Sudoku Tips 1

In diagram 2 you can see I have marked 2 columns A and B, these both have the most numbers in them, each having 6 pre-filled cells. Let’s see if that can help us in solving the puzzle?
Look at column A, remember it needs to have the numbers 1 to 9 in each column. And you can see that it already has pre-filled 3,9,5,2,6 and 7 thus this column is missing 1,4 and 8. Starting with the box that I have highlighted in yellow in diag.2 you can see that there is probably too many numbers missing in this box to try to use this to eliminate possibilities at this point. Similarly, the other 2 boxes underneath it, also have quite a few empty cells.
Let’s look at column B, we can see as it is already pre-filled with 7,4,6,2,5 and 1, it is missing the numbers: 3, 8 and 9.

Now before we continue, I want to put in my second of the Sudoku tips: Use a pencil to make notations in the grid, of possibles So you can rub it out once you know the answer definitely and also so you can keep track of what you have eliminated so far.

Diagram 3 – Using Notations

In diagram 3, you can see this tip in action.
If column B needs to be filled with 3, 8 and 9. Look at the first box (top right-hand corner), and you will notice there is already a 9 there, but not a 3 or 8. So the cell in the column B in this box, could be filled with either 3 or 8 and still adhere to the Sudoku rules. And so I put these possibilities in as temporary notation ’3,8′, see diagram 3. Now you repeat this elimination and scanning process on the other boxes that contain the cells in column B. As it is the box underneath has all the column B cells pre-filled. But the bottom right-hand box has empty column B cells. We can see that this box already has an 8 in it so the 2 empty cells that are in column B must be for either 3 or 9, so I have put in the notation ’3,9′ as possibilities, see diagram 4.

Diagram 4 – Sudoku Solving Techniques

And so now column B has been scanned and the possibilities have been entered as notes. Obviously if you are doing it on paper do it in pencil and around the edges so you can rub it out and put in the actual answer once you know, in pen.

Sudoku Tips 3: For easy Sudoku, I usually only put in possible numbers when I have whittled it down to 2 possibilities, anymore and your grid can get quite cluttered up with notes. However for more difficult Sudoku you may find you have to note where you have more possibles in order to get anywhere with it!

Now we have looked at column B and noted the result of our eliminations, lets go back and see what this has uncovered. In the top right hand box, where we have noted ’3,8′ you can see that there is already an ’3′ in that row, so by elimination and adhering to the Sudoku rules, only an 8 can go in that cell, see diagram 5. Can I repeat this process to use the notations in the bottom right hand box? No there are still too many unknowns in this box.

Diagram 5 – Elimination and Scanning

However, I can now also continue to see if my notations in column B have opened possibles in the other box that contains it, ie the middle right hand box. This box is missing 1,3,4 and 9. Now we look at each of these numbers to see if they already occur in other columns and rows that make up this box. And you will see that the 1 could be put in any of the 4 empty cells (and not break the Sudoku rule of one occurrence per row, column and box). The number 3 could be in 3 of the 4 empty cells, it can’t go in the middle right cell because there is a 3 in that row already. Similarly, the 4 can only go in 3 of 4 cells, because the row for the bottom right corner of this box, has a 4 already in that row. And lastly, look at the number 9. However you can see it already occurs in 2 of the 3 columns of this box. So there is only one empty cell left that the 9 can be in without breaking the Sudoku rules. These 3 deductions have been included in diagram 6.

Diagram 6 – Using your Notes

As you can see this is just a step by step how to start a Sudoku puzzle, and is already quite a long post, so I will stop at this point for now. But will continue with this step by step tutorial in my next post. What you will find is that with this method of scanning and eliminating you can continue with this puzzle and solve it yourself. With practise you will be able to solve Sudoku quickly and will become an expert at spotting the best place to start a Sudoku.

Once you have mastered the basics you will be able to move to more difficult Sudoku and then onto advanced Sudoku techniques. For a recap of the Sudoku rules, checkout my previous post.

Step by Step How to Solve Easy Sudoku (1 of 3) – Strategy Tips and Rules

In this post I’ll go over some simple Sudoku strategy tips based on the main Sudoku rules.  Sudoku is a simple yet entertaining logic game which anyone with a bit of spare time can enjoy. Though they vary in difficulty, the basic rules of Sudoku are the same and are easy to pick up.
The Sudoku grid is made up of 9 3×3 boxes which are arranged to make a 9×9 grid. (See diagram 1).

Diagram1 - Sudoku Grid

The main Sudoku rules:
1. The numbers 1-9 must all appear in each row, column and 3×3 box of the 9×9 grid.
2. The numbers 1 to 9 can only appear once in each row, column and 3×3 box of the 9×9 grid.
3. There is only one solution to a Sudoku puzzle.
By applying these rules it is possible to deduce and eliminate squares where a number a. couldn’t appear or b. could appear based on whether that number is already in the column, row, or 3×3 box.
This is an overview of the basic principles of Sudoku, which are relevant whether you are doing easy or advanced puzzles. In the next few posts, I will be working through a variety of Sudoku puzzles with a step by step guide on how to solve Sudoku.

Sudoku Basics – Sudoku Strategy Tips using the Sudoku Rules

In this how to solve Sudoku blog, I hope to include tutorials and tips to solve all sorts of puzzles from easy to advanced Sudoku. Starting with a step by step tutorial covering the basics and using the 3 main rules of Sudoku solving.

For the basics I will be writing about how to get started with a basic Sudoku puzzle, the Sudoku rules and concepts behind Sudoku puzzles. This will also include tricks in using naked singles, scanning and elimination.

For medium Sudoku techniques I’ll be including tutorials that use techniques such as naked paid, triplets, quadruplets. And also hidden pairs and triplets.

And for the advanced Sudoku techniques, I’ll be looking at X Wing (Column and Row), Sword Fish (Column and Row), Jelly Fish, XY Wing, XYZ Wing and WXYZ Wing.

Finally for the Sudoku addict very advanced Sudoku strategy tips will include linked pairs, bi-location graphs and Nishio.

With each advanced Sudoku tutorial I’ll be including step by step diagrams to make it easier to follow and understand the Sudoku strategy described in each tutorial.

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