The Hidden Triples Technique in Sudoku

Core Principle

Hidden Triples operate as Hidden Pairs do, but with three cells and three candidates within those cells in a house (row, column, or block). These candidates need to fully occupy the space labeled “triple”, allowing other numbers in the designated cells to be skipped.

Example 1 (Block 7)

In B7, candidates 2, 4, and 5 are exclusively located in R8C2, R9C2, and R9C3. While 1 and 6 will still occupy these cells, due to the triples exclusivity:

1 can be eliminated from R9C2
6 can be eliminated from R9C3
The puzzle becomes easier with these eliminations.

Sudoku rule Hidden Triples

Example 2 (Column 6)

In C6, candidates 2, 5, and 6 are restricted to cells R4C6, R6C6, and R8C6 (abbreviated as R468C6). Despite the puzzle having no initial singles, identifying this triple breaks it open, requiring only basic moves afterward.