GridWits
Easy tier Technique 3 of 20 Used by Smart Hint

Hidden Single

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

How it works

  1. 1The 22-in-three across run has two combinations, 5+8+9 and 6+7+9, so a 9 turns up in it either way.
  2. 2The first cell heads a 9-in-two down run, and a 9 there would need a 0 beside it — so that cell tops out at 8.
  3. 3The second heads an 8-in-two down run, so it tops out at 7 for the same reason.
  4. 4The run's guaranteed 9 has only the third cell left to live in. Place it.
9 8 22 5 6 7 8 5 6 7 5 6 7 8 9
  • Cells that establish the pattern
  • Where the conclusion lands
Next in the ladder Combination Elimination →

A digit that appears in none of this run's remaining sum combinations can be ruled out of every cell in it.