Naked Triple
A Naked Triple (also called an Obvious Triple) is the naked pair's bigger sibling. Where a naked pair locks two digits into two cells, a naked triple locks three digits into three cells — and clears those digits from everywhere else in the unit. It's a pure elimination technique, and once you're comfortable with pairs it's the natural next step.
What is a Naked Triple?
A Naked Triple appears when three cells in the same unit (row, column or box) together contain only three candidates between them — no others. The clever part: each cell doesn't have to show all three. Any mix works, as long as the three cells use just those three digits:
- {3, 8} {3, 9} {8, 9} — three cells, only the digits 3, 8 and 9
- {3, 8, 9} {3, 8} {8, 9} — also a valid triple
Because those three digits must fill those three cells (in some order), they are claimed — and can be removed from every other cell in the unit.
Step by step
- Fill in your pencil marks. Like all subset techniques, a naked triple is invisible until every candidate is on the board.
- Find two or three cells with small candidate lists in one unit — two or three candidates each.
- Check the union. If three cells use only three distinct digits between them, you have a naked triple.
- Eliminate those three digits from every other cell in the unit.
- Re-scan. The eliminations often expose a naked or hidden single straight away.
Indigo: the triple {3, 8, 9} spread across three cells. The green cell used to hold {5, 8}; removing the 8 leaves a Naked Single — 5.
Naked triple vs hidden triple
Don't confuse the two. A naked triple is three cells that contain only the three digits. A hidden version works the other way round: three digits that appear in only three cells, buried among other candidates. Naked triples are usually easier to spot — the short candidate lists give them away.
Common mistakes
- Counting four digits. If the three cells use four or more distinct candidates between them, it isn't a triple — keep looking.
- Expecting all three digits in every cell. They rarely are. {3,8}, {3,9}, {8,9} is a perfect triple even though no cell shows all three.
- Forgetting to re-scan. The point of the triple is the eliminations it triggers elsewhere — check the unit again straight after.
Which Sudoku types is this best for?
The same logic applies across variants, but it pays off more in some than others.