GridWits
Easy tier Technique 2 of 20 Used by Smart Hint

Single Combination

This run's remaining sum has exactly one digit combination left — every empty cell must draw from it. The classic "17 in two cells is 8+9" move.

How it works

  1. 1Two cells must sum to 17 with distinct digits 1-9.
  2. 2There's exactly one way: 8 + 9. Which cell gets which isn't known yet, but neither can hold anything else.
  3. 3Pencil both cells down to {8, 9}. The same idea powers every "magic" clue — 3, 4, 16, 17 in two cells; 6, 7, 23, 24 in three.
17 8 9 8 9
  • Cells that establish the pattern
Next in the ladder Hidden Single →

A digit guaranteed to appear somewhere in this run has only one cell left that can hold it.