The Naked Triplet technique identifies three cells in a row, column, or block that together contain exactly three distinct candidates. These candidates must occupy those cells, allowing you to remove the same candidates from other cells in the same row, column, or block.
- Row-based Triplet: If three cells in a row contain only three unique candidates, those candidates can be removed from other cells in that row.
- Column-based Triplet: If three cells in a column contain only three unique candidates, those candidates can be removed from other cells in that column.
- Block-based Triplet: If three cells in a block contain only three unique candidates, those candidates can be removed from other cells in that block.
Column 1 contains a Naked Triplet with the numbers 2, 4, and 5. Row 2: 2 and 4, Row 6: 2 and 5, Row 9: 4 and 5. This tells us these three cells will contain 2, 4, and 5, we just don't know in what order. From top to bottom it could be (2, 5, 4) or (4, 2, 5), but either way, 2, 4, and 5 must not exist in rows 7 or 8 in this column, so we can remove them as candidates there. This leaves us with a Naked Single of 7 in row 7, column 1, and the rest of the puzzle is easily solved from there with only the Naked Single technique.
This puzzle also includes other techniques such as Naked Single, Hidden Single, and Naked Pair. Practice applying multiple strategies to improve your solving skills!
How to spot it
Find three cells in one unit whose candidates, taken together, use only three distinct digits. Each cell may show two or three of them; the union is what matters.
When to use it
Apply it when pairs are exhausted. Triplets are easy to miss because the three cells need not show identical candidates.
Common mistakes
- Expecting all three cells to contain all three digits; they only need to collectively contain exactly three digits and nothing else.
- Counting a fourth digit by mistake; if the three cells contain four or more distinct candidates, it is not a Naked Triplet.
Frequently asked questions
- What is a Naked Triplet in Sudoku?
- A Naked Triplet is three cells in the same unit that together contain only three candidate digits. Those three digits are locked into those three cells, so they can be removed from every other cell in the unit.
- Do all three cells of a Naked Triplet need the same candidates?
- No. Each cell can show any two or three of the three digits. What matters is that the union of all candidates across the three cells is exactly three digits.
- How is a Naked Triplet different from a Naked Pair?
- It is the same idea with three cells and three digits instead of two. Both remove their digits from the rest of the shared unit.