Difficulty
Hard
Sudoku technique guide
Hidden Triple
When the easy moves slow down, one clear pattern can make the next step feel possible again. Hidden Triple helps you spot what the grid is already telling you.
By the end, you will know what to notice, how the idea works and when it is worth using.
At a glance
Technique family
Hidden subsets
Purpose
Removes candidates
Typical puzzle stage
Middle to late
Frequency
Uncommon
Prerequisites
Hidden Pairs and candidate scanning
Why this technique matters
Hidden Triples extend the same logic as Hidden Pairs, but they reward careful counting rather than broad searching.
The idea in plain English
A Hidden Triple is three digits that can appear only in the same three cells of one unit. Any other candidates in those cells may be removed.
How to recognise it
Track positions for digits first. The cells may each contain additional candidates, so the pattern can be visually hidden.
Pause when you see this shape. You do not have to force it; just check whether the pattern is complete.
How the logic unfolds
Think of this as a short conversation with the grid. Take one check at a time, and let each answer tell you what to inspect next.
Start by. Pick a unit and identify missing digits with only two or three possible locations.
Then. Find three digits whose combined positions are exactly three cells.
Next. Confirm those digits have no fourth possible position in the unit.
Finally. Remove any candidates other than the triple digits from those three cells.
When it usually appears
Use it after simpler hidden singles and pairs fail, particularly in a unit with several tightly restricted digits.
Common traps
These are easy places to get turned around. They are useful checks, not signs that you are doing badly.
- Counting cells for each digit separately instead of checking their combined positions.
- Deleting a candidate that belongs to a fourth key digit not part of the triple.
Frequently asked questions
Can a hidden triple use two positions for one digit?
Yes, as long as all three digits together are confined to three cells.
Is it worth searching often?
Only once easier scans have been exhausted.
Quick takeaway
- A Hidden Triple belongs to the hidden subsets family.
- Its purpose is to remove candidates.
- Look for a complete pattern, not one that only nearly fits.
- It is most useful middle to late.
- Once you make the deduction, return to the simpler scans.