GridWits
Hard tier Technique 8 of 46 Used by Smart Hint

Hidden Triple

Same idea as Hidden Pair, but three digits are confined to the same three cells.

How it works

  1. 1This box is drawn in full. Digits 2, 6 and 8 show up only in A4, A5 and B5 — the other four empty cells have ruled all three out.
  2. 2Seven cells are still empty here, and the four left over share {1, 4, 5, 9} — four digits in four cells, a Naked Quad the ladder only reaches after Hidden Triple.
  3. 3So 2, 6 and 8 must fill A4, A5 and B5, and their extras go: A4 loses its 9 and B5 loses its 5.

Play a Sudoku that needs this technique →

A 1 B 2 C 3 D 4 E 5 F 6 G 7 H 8 I 9 2 6 8 9 1 4 5 3 2 8 2 5 6 8 1 4 9 7 1 5 9 4 5 9 2 6 8 2 8 2 6 8 9 5
  • Cells that establish the pattern
  • Candidate ruled out
Next in the ladder Naked Quad →

Four cells in a unit whose candidates combine to exactly four digits — eliminate those digits elsewhere in the unit.