Claiming Pair / Triple
All candidates for a digit in a row or column lie in one box, clearing that box.
Also known as: Box-Line Reduction, Locked Candidates Type 2, Claiming Line
Quick Summary
When all remaining candidates for a digit in a row or column are confined inside a single 3×3 box, that digit must land in that box, eliminating it from the rest of that box.
Understanding the Claiming Pair / Triple Technique
Claiming (also called Box-Line Reduction) is the inward mirror of Pointing. The logic flows inward: from the line into the box. If a row or column can only place a digit inside cells that belong to a single 3×3 box, that row/column 'claims' the digit for that box. Consequently, none of the other cells in that 3×3 box can contain that digit.
Visual Examples
Green cells highlight the Claiming Pair / Triple pattern, amber cells denote where candidates are affected, and struck-through pencil marks show the eliminations. Use the buttons or arrow keys to browse examples.
How to Spot & Solve a Claiming Pair / Triple (Step-by-Step Guide)
The complete visual scanning and logical deduction process to execute this technique:
- 1Scan a row or column and focus on one candidate digit.
- 2Check if every remaining candidate for that digit in the line is trapped within the same 3×3 box.
- 3Because the row or column must contain that digit somewhere, it is guaranteed to land inside that specific box.
- 4Since that 3×3 box can only contain the digit once, none of the other cells in the box can take it.
- 5Eliminate that candidate from all other cells in the box that lie outside the original row or column.
Common Traps & Mistakes to Avoid
- Scanning only rows and forgetting to check columns.
- Failing to notice an extra candidate hiding in another box along the same row.
- Confusing Claiming with Pointing, leading to incorrect eliminations outside the box.
Frequently Asked Questions
Why is it called 'Claiming'?
Because the row or column 'claims' the digit inside that 3×3 box, preventing any other row or column in that box from claiming it.
Is Box-Line Reduction the same as Claiming?
Yes, 'Box-Line Reduction' is the formal mathematical name for Claiming, while 'Pointing' is sometimes called Line-Box Reduction.
Can Claiming involve three cells?
Yes, a Claiming Triple occurs when three cells in a row or column all share the same box. The eliminations in the rest of the box are identical.
Related Solving Techniques
Expand your repertoire by learning prerequisites and advanced counterparts:
Ready to Practice Claiming Pair / Triple?
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