Academy
ClaimingClaiming sudoku technique
Claiming is the mirror image of the pointing pair. This time you scan a row or column: if every place a digit can still occupy on that line falls inside a single 3×3 box, then the line has claimed the digit for those cells. The box must give up the digit everywhere else — its other two mini-rows lose the candidate.
How to find a claiming
- Pick a line — a row or a column — and a digit it still needs.
- Mark where on the line the digit can go.
- If all the marks fall inside one box, erase the digit from the other cells of that box.
- Follow up inside the box: the eliminations often leave a hidden single behind.
The pattern on the grid
A real position — every pencil mark computed, every red candidate a verified elimination. Toggle to see the grid after the move.
Locked Candidates (Claiming) on 1 in r9: r9c7, r9c9 => r7c7<>1, r7c8<>1, r7c9<>1, r8c7<>1, r8c8<>1, r8c9<>1
534719286896000000127068400482197653315826040769003020200670000600980000908004060
Standard 81-character format (0 = empty) — paste it into your solver of choice and verify the move yourself.
Worked example
Digit 1 in this position has its candidates at r9c7, r9c9 — the line confines the digit to one box. That intersection must receive the 1, so the remaining candidates fall: r7c7<>1, r7c8<>1, r7c9<>1, r8c7<>1, r8c8<>1, r8c9<>1. Nothing else about the position matters; the overlap alone carries the argument.
When it fails
Do not mix up the direction of the eliminations: claiming clears the BOX (outside the shared cells), pointing clears the LINE. Erasing along the row here would be wrong — the row is the side making the claim.