Sudoku Dragon for a free 23 day trial on your PC. It has all the features you need to solve puzzles whether you all options strategies explained new to Sudoku or an expert.

The software is designed for ease of update, and even within the generous free trial you can get all the available software upgrades for free. There are only a few strategies that you need to know in order to solve Sudoku puzzles. There follows a summary of the techniques you may find useful up to ‘advanced’ level. There may be only one possible choice for a particular Sudoku square.

You can use this technique by scanning for 8 allocated squares in all rows, columns or regions. When you look at individual squares you will often find that there is only one possibility left for the square. Because of the way that groups intersect you may have a group with more than one unallocated square and yet only one possibility exists for one of the squares. So there is only one possibility for that square, and the number must go there.

When all else fails, there are ‘naked chains’ and ‘hidden chains’. If you choose a wrong option at some stage later you will find a logical inconsistency and have to go back; they require a lot more thought and analysis to learn about and use correctly. There is one technique that is guaranteed all options strategies explained always work, this is a completely different type of strategy as it uses ‘brute force’ rather than ‘logic’. To use this technique you choose a promising square and mentally run through each number in turn that might go in it, a couple of examples follow to explain it.

In this partially solved Sudoku there are quite a few readily solvable squares. 7 and 9 as possibilities. The single possibility rule can be used to solve all the puzzle squares highlighted in green, so that makes it a very useful technique to have up your sleeve. To use this technique you choose a promising square and mentally run through each number in turn that might go in it, if there is only one number left then that number must go in the square. Often you will find within a group of Sudoku squares that there is only one place that can take a particular number. This is different to the ‘single possibility’ rule where we looked at squares on their own rather than as a group. The missing numbers are 1 and 3.

You will often find that the same square can be solved by the ‘single possibility’ rule as well as the ‘only square’ rule. It doesn’t matter which rule you use, as long as the square is solved. Whenever there are eight allocated in a group with only one remaining empty you can assign a symbol by applying either the ‘only choice’, ‘single possibility’ or ‘only square’ rules as all of them come down to the same thing. Sudoku allows squares to be solved in different ways using different strategies.

All stock market trading classes in pune strategies explained the logic applies equally for chains as it does for twins, a better name for this strategy might be ‘Box’ as you are looking for four squares forming the corners of a box. It is the complete Sudoku package, it is an application of logic that knocks out options that at first sight looked possible. Whenever there are eight allocated in a group with only one remaining empty you can assign a symbol by applying either the ‘only choice’, so the square can be safely set to the remaining option. The same sort of rule applies to quadruplets, if the two squares have another possible number then this number can be safely eliminated as an option. By excluding one possibility for a square may mean there is only one remaining possibility, the two ‘twin’ rules are particular examples of the general Sudoku logic. The term X, look at this 4×4 grid. One of the more complex Sudoku strategies is the ‘X, sudoku Dragon for a free 23 day trial on your PC.

Have you mastered all the strategies for solving Sudoku? Our strategy page gives an introduction to all the main tactics for solving a Sudoku puzzle. We have separate pages on Trial and error as well as Advanced Strategies. Sudoku puzzles download and install Sudoku Dragon. It is the complete Sudoku package, including hints, guides, and many new puzzle types. Sudoku puzzle solver for a free 23 day trial. Interested in something to brighten up your screen?

Some Sudoku authors refer to it as ‘slicing and slotting’. It is a quick way of solving squares as it can be done in your head by scanning the puzzle grid. It almost always finds a square or two that can be solved. At the heart of the technique is to take groups of three rows and columns in turn, working methodically through the whole grid. First look for all the 1s then all the 2s, 3s etc. The procedure is to scan rows and columns in groups of three and look to see where if anywhere the number being scanned has been allocated.

It will find squares that you could also have found using the only choice, only square and single possibility strategies. The way it works is that three rows or columns consist of three regions each of these can only take the symbol once. This takes a lot more explanation as instead of ‘forcing’ a number in a square, it is an application of logic that knocks out options that at first sight looked possible. By excluding one possibility for a square may mean there is only one remaining possibility, so the square can be safely set to the remaining option. Here’s an example of the sub-group rule. Ever wondered about the origins of Sudoku? Discover the long history of Sudoku on our History page.

Every row and column has three sub-groups in the three regions it crosses. Every square in the grid belongs to two sub-groups — one for the column it is in and one for the row it is in. The sub-group exclusion strategy is when you can prove that a number occurs in one of the sub-group squares even though it can’t be deduced which of the three sub-group squares it does go in. This may not solve a square, but it narrows down the possibilities. A couple of examples follow to explain it. Sudoku Dragon has been used with possibilities enabled and exclusions switched on so that the grid directly shows the squares where the exclusion rule comes into play.