Claiming in Sudoku: How Claiming Pairs and Triples Eliminate Candidates

If you already understand singles and basic note-taking, the next useful step is learning claiming in Sudoku. This technique, also called a claiming pair or claiming triple, helps you remove candidates when a digit is forced into one row or one column inside a single 3×3 box.

Claiming does not place a number right away in most cases. It clears false options. That cleanup often exposes a hidden single, a naked single, or an easier follow-up elimination in the next scan.

Many players first meet claiming as part of the broader locked candidates family. The good news is that the logic is simpler than the name sounds.

Claiming in Sudoku: Quick Answer

Claiming in Sudoku happens when all possible positions for a digit inside a 3×3 box fall in the same row or the same column. Because that digit must be placed inside the box, it can be removed from the rest of that row or column outside the box.

  • Claiming pair: the digit appears in exactly two cells in the box, and both cells are in the same row or column.
  • Claiming triple: the digit appears in exactly three cells in the box, and all three cells are in the same row or column.

In both cases, the elimination happens outside the box, along that shared row or column.

What Is Claiming in Sudoku?

Every 3×3 box must contain the digits 1 through 9 exactly once. If one missing digit can go only in cells that line up on the same row, then that box effectively claims the digit for that row position inside the box. The rest of the row, outside the box, can no longer contain that digit.

The same idea works for columns. If all candidates for a digit inside one box lie on a single column, remove that digit from the rest of that column outside the box.

Why It Works

  1. A digit must appear somewhere inside the box.
  2. Inside that box, every valid spot for the digit lies on one row or one column.
  3. That means the digit is locked to that line within the box.
  4. So any matching candidate on the same line outside the box is impossible.

This is pure logic, not guessing. You are using the overlap between a box and a row or column to eliminate false candidates.

Claiming Pair vs Claiming Triple

Claiming Pair

A claiming pair appears when a digit has exactly two possible cells in a box, and those two cells share one row or one column.

Claiming Triple

A claiming triple works the same way, except the digit has three possible cells in the box and all three line up on the same row or column.

The solving action is identical in both cases: remove that digit from the rest of the shared row or column outside the box.

How to Find Claiming in Sudoku

1. Start With One Box

Claiming is easiest when you focus on a single 3×3 box. List the missing digits and look at where each one can still go.

2. Track One Digit at a Time

Do not compare whole cells first. Instead, ask: Where can digit 7 go in this box? Then repeat for the other missing digits.

3. Check for a Shared Row or Column

If all candidates for one digit in the box line up on the same row or column, you have a claiming pattern.

4. Eliminate Outside the Box

Now move along that same row or column and remove the digit from every candidate cell that sits outside the box.

5. Re-Scan for Singles

Claiming often creates a simple follow-up move. After every elimination, check for hidden singles, naked singles, or a cleaner pair structure.

Step-by-Step Claiming Example

Imagine the top-left 3×3 box is missing the digit 6. Inside that box, candidate 6 appears only in cells R2C1 and R2C3.

Those two cells are both in row 2. That means row 2 must contain the digit 6 inside this box, in one of those two spots.

So any other 6 candidate elsewhere in row 2, outside this box, is false and can be removed.

The same logic works if the two or three candidate cells line up vertically in a single column.

Claiming vs Pointing Pairs

Players often confuse these two because both belong to locked candidates.

Claiming

You start from the box. A digit is confined to one row or column inside the box, so you eliminate that digit from the rest of the line outside the box.

Pointing

You still notice the box alignment, but the emphasis is usually described from the box projecting outward. In practical solving, the move feels very similar.

If you want the companion technique, read Pointing Pairs in Sudoku. Together, pointing and claiming are often taught as one family because they use the same box-line overlap logic.

When Claiming Shows Up Most Often

Medium Puzzles With Clean Notes

Claiming appears often once puzzles move beyond beginner singles. It is especially common in medium grids where the board is not yet crowded with more advanced patterns.

Right After a Fresh Placement

One solved cell can suddenly restrict a box so that a digit lines up on one row or column. That is a common moment for claiming to appear.

After Crosshatching or Basic Scanning

If you use crosshatching well, you often create the candidate restrictions that make claiming visible.

Common Claiming Mistakes

1. Eliminating Inside the Box Instead of Outside It

The claiming move removes candidates from the shared row or column outside the box. The box candidates are the reason the move works, not the cells you delete from first.

2. Using Outdated Notes

Claiming depends on accurate candidates. If your notes are stale, you may see a false pattern.

3. Forcing the Pattern When One Candidate Sits Off the Line

If even one valid candidate for the digit sits elsewhere in the box, the claiming pattern is not real. All candidates for that digit in the box must align on the same row or column.

4. Hunting Claiming Too Early

If the puzzle still offers easy singles, take those first. Claiming is efficient, but only after the simplest moves are gone.

Best Solving Routine for Claiming

  1. Clear obvious singles first.
  2. Update notes carefully.
  3. Scan each 3×3 box for missing digits.
  4. Check whether any one digit is confined to a single row or column in that box.
  5. Eliminate matching candidates outside the box.
  6. Return to easier logic before searching for another claiming pattern.

This fits well with a broader Sudoku strategy order of operations. Claiming is usually a middle step, not the first thing you check and not the last thing you learn.

FAQ: Claiming in Sudoku

What is claiming in Sudoku?

Claiming is a locked candidates technique where all possible positions for a digit inside one 3×3 box lie on the same row or column, allowing you to remove that digit from the rest of the line outside the box.

What is a claiming pair in Sudoku?

A claiming pair happens when a digit appears in exactly two candidate cells inside a box and both cells share one row or one column.

What is a claiming triple in Sudoku?

A claiming triple is the same idea with three aligned candidate cells in one box.

Is claiming the same as pointing pairs?

They are closely related and both belong to locked candidates, but many guides describe them from slightly different directions. In practice, both use the overlap between boxes and lines to eliminate candidates.

Do I need notes to use claiming in Sudoku?

Yes, in most cases. Claiming is much easier to spot when candidate notes are current and complete.

Conclusion

Claiming in Sudoku is one of the most useful intermediate techniques because it is simple, repeatable, and often productive on medium and hard puzzles. Once you learn to scan one box at a time and track one digit at a time, claiming stops feeling advanced and starts feeling routine.

If you want to improve faster, combine claiming with clean notes, careful rescans, and a fixed solving order. Then practice on fresh puzzles at Pure Sudoku and look for the moment when a box quietly locks a digit onto one line.