How to solve a hidden triple in Sudoku
A hidden triple is three digits that can only go in the same three cells of a unit, so those cells can hold nothing else.
How it works
When three digits are confined to the same three cells of a unit, those cells must hold exactly those digits.
Any other candidates in those three cells can be removed.
How to spot it
In a unit, list each digit that appears in two or three cells, and look for three digits that share the same three cells.
A worked example
This is a step from a real puzzle, a moment where the next move needs a hidden triple.
Struck-through digits are the ones that can be removed.
In column 7, 4, 5, 6 can only go in R1C7, R2C7, R3C7, so those cells can hold nothing else. Remove the other notes from them.
Where it fits in Rocksled Sudoku
Puzzles that need a hidden triple are never rated below Expert. Each step of this kind adds 50 points to a puzzle’s difficulty score. When you ask for a hint that needs it, the game names the technique and shows the cells involved. See how to play for the rest of the controls.