Hidden Triple
Three digits that can live in only the same three cells of a unit — clearing every other candidate from those cells.
A hidden triple is the mirror of a naked triple. Three digits can each be placed in only the same three cells of a unit (no single cell needs all three), so those three cells must hold those three digits between them. Every other candidate can be erased from the three cells.
It is "hidden" because the three cells usually carry extra pencil marks; the triple is revealed only by tracking where each digit is allowed to go.
How to spot it
For a unit, list the candidate cells of every digit. If three digits are collectively restricted to the same three cells — appearing in no other cell of the unit — those cells form a hidden triple. Keep only those three digits in them and strike out the rest.
- Track candidate cells for each digit in the unit.
- Find three digits confined to the same three cells.
- Delete all other candidates from those three cells.
Worked example
- In a box, digits 2, 6 and 9 each appear only in cells A, B and C.
- No other cell in the box can hold 2, 6 or 9.
- So {2,6,9} are locked into A, B and C.
- A still showed {2,4,6,7,9}; remove 4 and 7, leaving {2,6,9}.
- The cleared marks often expose a single or pair elsewhere.
Try it yourself
Tap a cell, then a number, to practise.
Frequently asked questions
- How is this different from a naked triple?
- A naked triple is found from cells whose candidates already total three digits; a hidden triple is found from three digits that can live in only three cells, even when those cells show more marks.
- Do all three digits need to appear in all three cells?
- No. Each digit must be confined to those three cells, but any individual cell may contain only two of them.
Related techniques
Practice: Hidden Triple
Put the Hidden Triple to work on a live board — free puzzles with notes, hints and four difficulty levels.
Try it on a live board