The solving techniques are identical to those of a classic sudoku.

You can find many more puzzles on the internet, in a whole range of difficulty levels.A hexadoku is a 16x16 sudoku puzzle instead of 9 x 9 squares. If you reach a contradiction (a repeated digit in a row, column, or block), you should retrace your steps and undo what you've done until you have no contradiction.Įxercise: Here is a Sudoku puzzle for you to try: Continue playing, using the strategies above and any other ones you discover. If no entries are forced, try to pick a box with the fewest number of possibilities and pick one of them. Similarly, a triple of cells having only three possibilities of entries between them will eliminate these entries in all other cells in a neighborhood of this triple. This will decrease the number of possibilities for the other cells in the neighborhood and help you get closer to a solution. What you can still gain from this observation is that those pair of numbers cannot occur anywhere else in the neighborhood. You might find that a pair of cells has only two options of entries, but don't know which goes where. One more complicated strategy is to look at pairs or triples of cells within a row, column, or block. You often need more complicated analysis methods to make progress, and sometimes you need to make a guess and proceed, backtracking if the guess results in a conflict. These two strategies are usually not enough to completely fill in a Sudoku grid. Once you've done this, the chosen number can be eliminated from being a possibility for any other cell in the neighborhood. If the digit can only be placed in one cell in the neighborhood, you should fill that cell in. Note all the cells in the row, column, or block in which the number can be placed without violating the One Rule. If a cell ends up having only one possible entry, it is a 'forced' entry that you should fill in.Īnother way to proceed is to pick a number and a row, column, or block. The most basic strategy to solve a Sudoku puzzle is to first write down, in each empty cell, all possible entries that will not contradict the One Rule with respect to the given cells. In fact, mathematical thinking in the form of logical deduction is very useful in solving Sudokus. Any nine symbols would serve just as well to create and solve the puzzles. The puzzle does not depend on the fact that the nine placeholders used are the digits from 1 to 9. When one hears that no math is required to solve Sudoku, what is really meant is that no arithmetic is required.

Sudoku with solution