Sudoku Tips and Tricks

This video shows the same technique used by the Obvious pairs and triples, only with 4 distinct numbers within the same row, column or block.

In this video, we are going to show you how the obvious quadruple technique works. This technique is very similar to the obvious triples, but it involves 4 numbers, instead of 3.

An obvious quadruple is a set of four cells that belong to the same row, column, or block, and whose set formed by their combined candidate values contains a total of four distinct numbers. In this case, these are numbers 2, 6, 7, and 9 in the upper left block.

Each cell can contain either all four numbers, or only two or three of the four, as long as the previous condition is met and applied on the entire quadruple (four distinct numbers in total).
Therefore, they can be eliminated as candidates from all other cells of the row, column, or block.

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