Peak Sudoku

Hidden Triple

Three digits confined to the same three cells of a house, clearing all other candidates from those cells.
All techniques

Overview

Tier 3
Subsets
Typical difficulty
Peak Score 45–60
Also known as
Concealed Triple, Hidden Triplet

When three digits in a house only appear in three cells, those three cells must hold those three digits. All other candidates can be wiped from those three cells.

Hidden Triples require systematic candidate tracking. If three digits (e.g. {2, 6, 8}) are confined exclusively to a group of three cells in a row, column, or box, no other digits can occupy those cells. Solvers eliminate all other candidates from the three cells, leaving behind a clean Naked Triple.

Worked examples

1 / 5
Reading the exampleCells losing candidatesEliminated candidates
In the bottom-left box, the digits 1, 2 and 7 can only go in R7C1, R8C2 and R8C3. Those three cells must take those three digits, so every other candidate can be removed from them.
Removes: 5 from R7C1 · 6 from R7C1, R8C2, R8C3

How to apply it

Spotting the pattern and making the deduction, in order.

  1. Scan a row, column, or box for three digits that only appear in three specific cells across the entire unit.
  2. Verify that none of those three digits appear anywhere else in that row, column, or box.
  3. Because the unit must place all three digits, they will completely fill those three cells.
  4. Erase all other candidate pencil marks from those three cells.

Common mistakes

  • Overlooking an occurrence of one of the digits in a fourth cell in the house.
  • Thinking all three digits must appear in every cell of the triple.
  • Failing to erase the surplus candidates from the three cells.

Frequently asked questions

Can a Hidden Triple have cells with only two candidates?
Yes. For example, three cells could hold extra candidates alongside the three core numbers. As long as those three core numbers appear nowhere else in that unit, all other candidates in those cells are eliminated.
Peak Score 35–50Hidden PairTwo digits in a house that can only go in the same two cells, clearing all other candidates from those cells.Peak Score 40–55Naked TripleThree cells in a house whose candidates are drawn from the same three digits.Peak Score 55–70Hidden QuadFour digits confined to the same four cells of a house, clearing all other candidates.

Put Hidden Triple into practice

Try a puzzle from the Tricky tier (Peak Score 41–50).

Play a Tricky puzzleAll 25 techniques