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Hidden Triple

Hidden TripleSTEP 0/3

Introduction

The Hidden Triple strategy works similarly to Hidden Pairs, but this time we are looking for three candidates hidden in three cells within the same area.

We look for an area (row, column, or box) where three specific candidates can appear only in three cells.
These cells may also contain other candidates. This is exactly why our triple is hidden among the other possibilities.

Since these three specific digits have no other possible positions in the area, they must be placed in exactly these three cells.

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Hidden TripleSTEP 1/3

Checking the Constraints

Look at Column 6. We can see three cells containing a larger number of candidates that deserve closer attention.

In Row 4, Column 6, we have candidates 1, 2, 4, 5, 6, 7, and 8.
In Row 6, Column 6, we have candidates 1, 2, 4, 5, 6, and 8.
In Row 8, Column 6, we have candidates 1, 2, 3, 4, 6, and 8.

At first glance, it is difficult to notice anything special. Let's check which cells can contain each of the individual digits.

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Hidden TripleSTEP 2/3

Finding the Hidden Triple

Let's now analyze candidates 2, 5, and 6. All three digits have very limited possibilities in Column 6.

Candidate 5 can only appear in Row 4, Column 6 or Row 6, Column 6.
Candidate 2 can only appear in Row 4, Column 6, Row 6, Column 6, or Row 8, Column 6.
Candidate 6 can also appear only in these three cells.

The digits 2, 5, and 6 are therefore completely confined to these three cells. This is our Hidden Triple.

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Hidden TripleSTEP 3/3

Analysis

Since the digits 2, 5, and 6 must be placed in these three cells, all the other candidates in these cells become unnecessary.

In Row 4, Column 6, we keep only candidates 2, 5, and 6.
In Row 6, Column 6, we also keep only candidates 2, 5, and 6.
In Row 8, Column 6, we keep only candidates 2 and 6.

We do not need to know which of the three cells will receive 2, 5, or 6. We only know that all three digits must be distributed among these three cells.

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