Claiming
MediumWhen, along a row (or column), every place left for a digit lies inside the same box, the digit of that line is in that box. So no other cell of the box can hold it. It is the mirror of pointing.
How to spot it
- With notes, look at where a digit can go along a row or a column.
- If all those cells sit in the same box, the line claims the digit there.
- Remove it from the other cells of that box.
Why it works
The row needs the digit once, and its only places are in one box. So that box gets its digit from this row, and nowhere else in the box can have it.
Example
6
3
8
2
5
6
4
9
3
8
8
7
3
6
2
3
6
7
9
1
6
3
9
3
8
6
3
4
5
6
5
6
3
4
2
6
4
3
5
Look at the 7s in column 2.
Common mistakes
- Mixing it up with pointing: here the row limits the box, there the box limits the row.
- Removing the digit from the rest of the row instead of the rest of the box.