Hidden Triple
Three digits confined to the same three cells of a house, buried among other candidates that can then be removed.
Digits 3, 6, and 7 in this box only appear across these three cells, each showing extra candidates too.
How to spot it
- 1Find three digits that only appear within the same three cells.
- 2Those cells are reserved for those digits.
- 3Clear every other candidate from those three cells.
When to use
Rarely, on expert grids when nothing simpler applies.
Common mistake
Giving up the search too early — hidden triples are easy to walk past.
Worked Example
Sometimes three digits are confined to the same three cells of a house, but each of those cells also shows extra, unrelated candidates — which hides the pattern. Suppose 3, 6, and 7 only ever appear as candidates across three particular cells of a box, even though those cells also carry a stray 1, 2, or 8.
Since 3, 6, and 7 have nowhere else to go but those three cells, the extra candidates serve no purpose and can be removed, leaving just those three digits distributed among the trio. Hidden triples are rare and easy to walk past — they only turn up on expert grids once everything simpler has been tried.