Claiming Pair
Prerequisites: Pointing Pair
Overview
When the only cells in a row or column that can hold a digit all lie in one box, the line's copy of that digit is in that box, so the digit can be crossed out of the rest of the box.
How It Works
A row needs each digit once. If every cell in the row that can hold a digit lies in the same box, the digit will land in that box, on this row. The box can hold only one copy, so its cells off the row can't have it: the row 'claims' the digit for the box. Columns work the same way.
When To Use It
Use it alongside Pointing Pairs once the singles run out. It is the same overlap of a box and a line, read from the line's side.
How To Detect It
For each row and column and each digit it is missing, look at the cells that can still take that digit. If they all sit in one box, remove the digit from the rest of that box.
Visual Example
Step 1 of 8
A Line Claims a Box
A Claiming Pair is the other half of box–line interaction. A Pointing Pair starts from a box: the box points along a line. A Claiming Pair starts from a line: if all of a digit's places in a row or column fall inside one box, the line claims that digit, and it can be removed from the rest of the box. You may also see these called Box/Line Reduction or Locked Candidates.
Practice
Your goal: fill the highlighted cell. Select a cell, then pick a number.
A Claiming Pair lets you eliminate inside a box. Use it, then fill the Naked Single that results.Candidates already ruled out by earlier techniques aren't shown.
Use it in a real game
Advanced puzzles are where these techniques start to matter.
Play an Advanced puzzle