Killer sudoku combinations

Killer sudoku also killer su dokusumdokusum dokusumokuaddokuor samunamupure is a puzzle that combines elements of sudoku and kakuro, killer sudoku combinations. Despite the name, the simpler killer sudokus can be easier to solve than regular sudokus, depending on the solver's skill at mental arithmetic ; the hardest ones, however, can take hours to solve. A typical problem is shown on the right, using colors to define the groups of cells. More often, puzzles are printed in killer sudoku combinations and white, with thin dotted lines used to outline the "cages" see below for terminology.

Killer Sudoku adds a new dimension to standard Sudoku, requiring arithmetic to solve. You will need new specialised Killer Sudoku solving techniques to progress in these puzzles besides the standard Sudoku techniques you will already know. An essential Killer Sudoku solving technique is the "45 rule". This uses the fact that every row, column and block must contain each of the numbers 1 to 9 once. Therefore, the total of all numbers in one row, column or block will always be Take the first column of the Killer Sudoku shown in Figure 1.

Killer sudoku combinations

Remembering common unique combinations is essential if you want to improve your time for solving killer sudoku puzzles. As well as cell cage combinations, we've included required digits further down. Some cells always require particular digits, regardless of the number combination that goes into them. Knowing these is a great way to eliminate candidate numbers from blocks, rows, and columns. Is it cheating? We call it a cheat sheet, but is it really cheating? Only you can decide! Our view is that a reference like this is no more cheating than using a dictionary to check your spelling. For us, puzzles like killer sudoku are all about the logic and not an exercise in memory or recall. New to killer sudoku? Be sure to check out our Killer Sudoku From Scratch tutorial. Love logic puzzles? Be sure to check out Puzzle Weekly — our free weekly collection, delivered to your inbox every Monday.

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Table of Contents Introduction Basic Solving Stragegies Example basic puzzle More advanced example based on weekly 24 More advanced example based on weekly 28 More advanced example based on weekly 74 A daily is easier than it looks More advanced example based on weekly Killer Sudoku Solving Strategies There are three basic methods used to solving killer sudoku puzzles. The first is to use the strategies for solving regular sudoku puzzles. The second is to consider the different ways that a sum can be created. The third is to consider the total value of a region. Here we outline the basic strategies and then show how they are applied in a sample puzzle. At a later date we will post more complex strategies. The Terminology used on this page is defined on the rules page. Basic Solving Strategies The following are the basic rules used to solve killer sudokus.

Killer sudoku combinations

Killer Combinations Each clue in each cage will give rise to a certain set of combinations of numbers for each cell. It is a convention of Killer Sudoku that no cage will duplicate a number even if it dog-legs through several 3 by 3 boxes. Some cages will not be very helpful but certain combinations, such as these listed here mean that the total number of possible numbers is equal to the cage size. In the first, for example, a clue of 3 in a cage of size 2 can only have 1 and 2 in it. These means you can remove 3 to 9 from those cells. I have written an example of the use of 'hard' Killer combinations on this page.

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For example: a 4 cell cage totaling 13 has the possible combinations of 1, 2, 3, 7 , 1, 2, 4, 6 , or 1, 3, 4, 5. You will need new specialised Killer Sudoku solving techniques to progress in these puzzles besides the standard Sudoku techniques you will already know. This can be useful if, for example, they have already deduced another cell within a nonet the cage resides in as having the number 1 as its solution. For an outside square, the solution is always the outside total — The player then knows for certain that one of the numbers within that cage is 1 no matter which is the final solution. The numbers in this column will add up to The four cells in the top right cage totaling 15 can only include one of 1, 3, 7, or 9 if at all because of the presence of 1, 3, 7, and 9 in the top right hand nonet. Call this the 'inside total', because it is the total of all cages which lie completely inside the column. This article has multiple issues. The biggest number an 'innie' or 'outie' can hold is 9, so adding or subtracting that value will change the last digit of the total in a way that no other value would - allowing the 'innie' or 'outie' to be directly calculated. Download as PDF Printable version. Is it cheating? An 8-cell cage is of course missing only one digit 45 minus the sum of the cage. Even though, initially, there is no way to tell which combination of numbers is correct, every solution available has a 1 in it.

If you've struggled to complete tricky, tough, or deadly Killer Sudoku puzzles then this App could be for you.

However, when The Times first introduced the killer sudoku on 31 August , the newspaper did not make this rule explicit. This article has multiple issues. Is it cheating? Download as PDF Printable version. A typical problem is shown on the right, using colors to define the groups of cells. If there is only one cell available, it is a 1. In the case, it was easier to calculate the inside total, but if the cage lying partly outside has one square outside and more than one square inside, the outside total should be used to calculate the outside square. Be sure to check out our Killer Sudoku From Scratch tutorial. A further technique can be derived from the knowledge that the numbers in all houses rows, columns and nonets add up to Clock arithmetic has the additional bonus that, when the final digits of two cage totals add up to 10 1 3 and 2 7 , for example , the pair will make no difference to the overall clock total, and can simply be skipped. By adding up the cages and single numbers in a particular house, the user can deduce the result of a single cell.