Locked Candidates Type 2 (Claiming)



Locked Candidates Type 2 (Claiming)

This method is somewhat the opposite of type 1.

If in a row (or a column) all candidates of a specific digit are in only one box, that digit can be eliminated from all other cells in this box.
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Take a look at row #3; we've done pencil marks for the whole row.

This row has to contain '3'. And it has to reside on one of these cells - R3C1 and R3C3.

Both these cells are in the same box - box #1.
Sudoku Locked Candidates type 2


Now take a look at box #1, we've marked the possible cells for '3'.

Since we already established that either R3C1 or R3C3 will be '3' - we can safely eliminate '3' from all the other cells in this box and particularly from R3C1.
Sudoku Locked Candidates type 2


Here's another example of locked candidates type2.

Take a look at column #1; we've done pencil marks for the whole row.

This row has to contain '1'. And it has to reside on one of these cells - R7C1 and R8C1.
Both these cells are in the same box - box #7.
Sudoku Locked Candidates type 2 - Second Example


Now take a look at box #7, we've marked the possible cells for '1'.

Since we already established that either R7C1 or R8C1 will be '1' - we can safely eliminate '1' from all other cells in this box.
Sudoku Locked Candidates type 2 - Second Example

How to Find Locked Candidates

Whenever a candidate is confined to one row or column within a box it has a chance to be a locked candidate.

But you don't have to use pencil marks to find them. Using highlights can be helpful.

Highlight a digit and consider the possibilities in your mind (demonstrated here).
How to find locked candidates?


If you see that a digit is confined to a specific row (as row #8 below) or column within a box, than this digit is blocked from the rest of the row (or column).
How to find locked candidates?

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