Hidden Triple in Sudoku: How to Spot It
Learn the Hidden Triple Sudoku technique: three numbers are limited to three cells, so extra candidates inside those cells can be removed.
Guided example
See the Hidden Triple on this board
Read this as one teaching unit: first identify the active unit, then the marked pattern cells, then the candidates removed or maintained.
Quick answer
A Hidden Triple in Sudoku is a set of three numbers that can only go in three cells of the same row, column, or box. Keep those three numbers in those cells and remove any extra candidates from the same cells.
How to spot it
Follow the board in order
- 1 Choose one row, column, or box and focus on three target numbers.
- 2 Mark every cell where those numbers can appear.
- 3 Confirm the three numbers are limited to the same three cells.
- 4 Remove all other candidates from those three cells.
What is a Hidden Triple?
A Hidden Triple appears when three numbers are restricted to the same three cells inside one row, column, or box.
The cells may show extra candidates, so the pattern is less obvious than a Naked Triple.
When to look for it
Look for Hidden Triples after Hidden Pairs are comfortable. They usually appear in puzzles where candidate notes are crowded and easier eliminations no longer help.
Scan one unit at a time. Instead of asking “what can this cell be?”, ask “where can these three numbers go?”
Example walkthrough
This walkthrough uses a real hard app puzzle tagged Hidden Triple. In row 8, digits 2, 5, and 8 are confined to r8c6, r8c7, and r8c9. Since those three digits must occupy those three cells, extra candidates inside the blue cells are crossed out.
Why the cleanup works
The three target numbers need three positions. In this app puzzle, if 2, 5, and 8 can only go in the blue cells, those cells are reserved for them.
An unrelated candidate inside a reserved cell cannot survive, because that cell must eventually hold one of the hidden-triple numbers.
Hidden Triple vs. Naked Triple
A Hidden Triple removes extra candidates from the triple cells.
A Naked Triple removes the triple numbers from other cells in the same unit.
Common mistake
Do not remove the hidden-triple numbers from the three blue cells. Those are the candidates you are keeping. Remove only the unrelated extras inside those cells.
FAQ
What is a Hidden Triple in Sudoku?
A Hidden Triple is three numbers that can only appear in three cells within one row, column, or box.
What gets eliminated in a Hidden Triple?
You remove extra candidates from the hidden-triple cells themselves, not from every other cell.
Why is it called hidden?
The triple is hidden because the cells may contain extra candidates that disguise the three-number pattern.
Should beginners learn Hidden Triples early?
No. Learn Hidden Singles, Naked Pairs, and Hidden Pairs first, then use Hidden Triples when easier scans stall.
In this lesson
- Board example: see the pattern first.
- Walkthrough: connect each highlight to the rule.
- FAQ: check edge cases after the move is clear.
Practice this technique in Sudoku Coach
Read the pattern, then practice it step by step with guided hints that explain why the move works.
Related Sudoku techniques
Hidden Pair in Sudoku: How to Spot It
Learn how Hidden Pairs work in Sudoku, why they are harder to see than Naked Pairs, and how to clean up candidates.
Naked Triple in Sudoku: How to Spot It
Learn the Naked Triple Sudoku technique: three cells in one unit reserve three candidates, allowing eliminations from the rest of that unit.
Naked Pair in Sudoku: How to Spot It
Learn how Naked Pairs work in Sudoku, when to look for them, and how to remove candidates safely.