Claiming (Locked Candidates)
A Sudoku solving technique · level 2 · first needed around SE grade 3
By The Hardest Sudoku Team · Last updated
TL;DR
Claiming is the mirror of pointing: when a digit's candidates in a row or column all fall inside one box, you eliminate that digit from the rest of that box.
How does the Claiming (Locked Candidates) work?
If a line (row or column) can only place a digit within the cells it shares with a single box, the digit is 'claimed' for that box on that line — so it cannot occupy the box's other cells.
When does it apply?
When a row or column restricts a digit to its intersection with one box.
A worked example
If 8 in a row can only go in the three cells the row shares with the center box, then 8 is removed from the rest of the center box.
See where this fits on the difficulty scale on the SE grade page, or browse every technique in the glossary.