Solving techniques
Hidden triple
The hidden triple is one of the harder patterns to see, because the cells show many extra candidates that hide it.
A hidden triple is three digits whose candidates appear in only three cells of a row, column or box. The three digits must fill those three cells, so every other candidate can be removed from them.
The logic
If three digits can only go in three cells of a unit, those cells are used up by them. Any other candidate in those cells is impossible. The cells need not contain all three digits each, but together they must cover all three.
How to find a hidden triple
- Choose a unit and write notes.
- For each digit, note which cells in the unit list it.
- Look for three digits with at most three cells in total.
- Remove all other candidates from those cells.
Common mistakes
- Missing a digit that is also a candidate in a fourth cell, which breaks the triple.
- Removing the three digits themselves instead of the others.
- Confusing it with a naked triple. In a naked triple the cells have only three digits. In a hidden triple, the digits have only three cells.
Related
See hidden pairs first, then compare with naked triples. Both appear in Hard puzzles.
Frequently asked questions
What is a hidden triple?
Three digits that can only go in the same three cells of a unit.
What do you remove?
Every other candidate from those three cells.
Is it rare?
It is less common than pairs, but it appears often in Hard puzzles.