The Hidden Triplet Technique helps you identify groups of three candidates that only appear within the same three cells of a row, column, or block. These three candidates must occupy those cells, and all other candidates can be eliminated from those same cells.
- Row-based Hidden Triplet: If three candidates only appear in three specific cells of a row, those cells can only contain these three candidates.
- Column-based Hidden Triplet: If three candidates only appear in three specific cells of a column, those cells are restricted to just these three candidates.
- Block-based Hidden Triplet: If three candidates only appear within three cells of a block, those three cells can only contain these candidates.
This puzzle contains a Column-based Hidden Triplet scenario where the numbers 1, 7, and 8 are only present in three specific cells of column 2. Therefore, these cells must contain the numbers 1, 7, 8, and all other candidates can be removed from these cells, such as the number 9 from row 4 and the number 3 from row 5.
This puzzle uses all Naked Singles along with the one Hidden Triplet technique.
How to spot it
In one unit, find three digits that are confined to the same three cells, even though those cells also hold other candidates.
When to use it
It is the three-digit version of the Hidden Pair; scan for it when a unit has a few digits clustered in the same handful of cells.
Common mistakes
- Requiring each of the three digits to appear in all three cells; they only need to be confined to those three cells collectively.
- Stopping at finding the triplet without removing the other candidates from the three cells.
Frequently asked questions
- What is a Hidden Triplet in Sudoku?
- A Hidden Triplet is three digits that can only be placed within the same three cells of a unit. Once identified, every other candidate is removed from those three cells.
- How do you spot a Hidden Triplet?
- List the possible cells for each digit in a unit. If three digits are restricted to the same three cells and appear nowhere else in the unit, you have a Hidden Triplet.
- Is a Hidden Triplet hard to find?
- It is one of the trickier basic techniques because the three cells usually contain extra candidates that disguise the pattern. Careful per-digit scanning reveals it.