The ‘Obvious Triples’ technique operates on a similar principle as the ‘Obvious Pairs’ method, but instead of looking for pairs, you need to identify three cells that contain the same set of candidate numbers.
While this method might seem complex at first, it becomes intuitive with practice. Let’s consider an example to clarify. As shown in image 1, fill all the cells with candidate numbers. As shown in image 2 focus on the 3×3 box highlighted with the purple frame. Here you see that there are three cells highlighted with the green frame that contain numbers 1, 4, and 8. Since these three cells can only be filled by either of them (1, 4, or 8), these numbers form our ‘Obvious triples.’
Next, examine the 3×3 block. Consequently, you can eliminate these three numbers from other cells as shown in image 3. This leaves us with the ‘Obvious Single’ in the middle bottom cell, which is the number 5. Afterward, remove 5 from the middle top cell which leaves us with another ‘Obvious Single’ that is the number 2. You can then confidently place 5 and 2 into their respective cells as shown in image 4.
The ‘Obvious Triples’ method is used to narrow down the possibilities by eliminating the duplicate values. Once you’ve become proficient with this method, you can try more challenging Sudoku puzzles by downloading our free printable Sudoku puzzle books.