Hidden triple
HardWhen three digits can only go in the same three cells of a row, a column or a box, those cells hold those three digits. Every other candidate in them can go. Like the naked triple, each digit doesn’t need all three cells.
How to spot it
- Pick a unit and, for each missing digit, look where its notes are.
- Find three digits whose places, put together, are only three cells.
- Remove every other candidate from those three cells.
Why it works
The three digits must each go somewhere in the unit, and they only have three cells between them, so they fill those cells. Nothing else can.
Example
5
9
3
1
9
6
1
1
8
6
9
3
6
4
8
1
5
8
9
1
3
4
6
1
6
9
4
5
3
8
9
1
6
1
2
5
1
4
6
3
Look at where 6, 8, and 9 can go in row 8.
Common mistakes
- Looking at cells instead of digits: a hidden triple is found by asking where each digit can go.
- Removing the three digits from other cells: they were already absent there, which is what makes the triple.