Hidden triples work like hidden pairs, but with three numbers and three cells. If three numbers can only appear in the same three cells, those cells belong to them.
What is a hidden triple?
In a row, column, or box, if three numbers are restricted to the same three cells, those cells must contain those numbers. All other candidates in those cells can be erased.
Numbers 1, 7, and 9 can only go in these three cells. Remove other candidates.
Naked vs hidden triples
Same as with pairs. Different starting point, same outcome.
Naked triple
Three cells show only three candidates. Remove those from other cells.
Hidden triple
Three candidates appear in only three cells. Remove other candidates from those cells.
How to find them
For each group, track where each number can go. If three numbers share the exact same three cells, you have a hidden triple.
- Pick a row, column, or box.
- List which cells can hold each missing number.
- Find three numbers that all appear in only the same three cells.
- Remove all other candidates from those three cells.
Only these three cells can hold 2, 6, and 7. Clean out the extra candidates.
Tips
- Hidden triples are rare but powerful. They usually unlock stuck puzzles.
- Focus on groups where several numbers are still missing.
- If you find two numbers sharing three cells, check if a third number joins them.
Practice
Hidden triples show up mostly in hard puzzles. The search takes time, but finding one often breaks the puzzle wide open.