GridWits
Medium tier Technique 9 of 31 Used by Smart Hint

Box-Line Reduction

A digit confined to one box within a row or column is eliminated from the rest of that box.

How it works

  1. 1The mirror image of a Pointing Pair. Take a row, and a digit whose remaining cells in that row all fall inside one box.
  2. 2The row must contain the digit, so it lands inside that box.
  3. 3Strike the digit from the box's other cells, the ones outside the row.
Next in the ladder Captured Candidates →

If every way of making a cage's total uses some digit, that digit is in the cage — and nowhere else in its house.