There are three fundamental ways to crack a tough sudoku problem, we have provided below our killer sudoku tips. Use the methods for conventional sudoku puzzles as a starting point. The second step is to think about the various ways that a sum can be produced. The third is to think about a region’s overall worth. Here, we’ll go through the fundamental tactics before demonstrating how to use them in a sample puzzle. Use these killer sudoku tips to master sudoku.

- Rule of 1;
- Rule of Necessity;
- Rule of 45;
- Rule of ‘K’; and
- Sum Elimination.

## Rule of 1

This is taken directly from the sudoku definition. There cannot be any duplicate digits in any region. Each digit appears exactly once in a sudoku area. For instance, if a digit is present in a row, it cannot be present in any other row cell. Similar to how each digit can only show up once in a cage. A digit cannot reappear in the same cage if it is already there.

## Rule of Necessity

This rule can be applied to a cage or to sudoku regions (such as a row, column, or nonet). Each zone in the first scenario must contain all one through nine digits. As a result, the missing digit must show up in the empty cell if all the other digits in a row but one do not.

## Rule of 45

The numbers one through nine are present in each sudoku region (i.e., row, column, or nonet). Thus, the total value for each sudoku region is 45. The cells that aren’t covered must add up to 45-S if S is the total of all the cages that are totally contained in a region.

## Rule of ‘K’

An extension of the Rule-of-1 is the Rule-of-k. No other cell in that region can contain any of the k values if a region has exactly k cells, each of which contains exactly k different possible values.

## Sum Elimination

This tactic looks at various potential approaches to construct a cage. It’s frequently possible to find a solution by limiting the number of distinct methods that can be used to calculate a total. The number of sums can be decreased in a variety of ways. For instance, there is only one set of values that can be used when a 2-cage totals 3, 4, 16, or 17. (3=2+1, 4=3+1, 16=9+7, and 17=9+8.) The following 3-cages have only 1 possible combination: 6=1+2+3, 7=1+2+4, 23=9+8+6, 24=9+8+7. The online player page’s sum calculator can be quite helpful.

Use the above Killer Sudoku tips and master the art of Sudoku.

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