Mental Royale
All techniques

Swordfish

Fish & Wings15 / 32

The X-Wing's big sibling: three rows locked to three columns.

Take three rows in which a digit is restricted to at most three cells each, all falling into the same three columns. Between them, those rows deliver the digit to all three columns.

The three columns are then fully supplied from inside the pattern, so all their other cells lose the digit. Rows and columns can swap roles, just like with the X-Wing.

See it in action

123456789
2
7
1
8
123456789
4
3
5
1
5
123456789
123456789
123456789
3
123456789
123456789
7
3
123456789
123456789
123456789
7
5
123456789
1
2
7
4
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3
9
123456789
123456789
123456789
1
2
123456789
123456789
7
1
4
3
5
123456789
123456789
3
1
123456789
5
8
123456789
7
4
4
1
2
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6
7
5
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3
8
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5
123456789
123456789
1
4
123456789
5
123456789
123456789
123456789
123456789
1
7
2
123456789

Step 1 of 4

The setup

For one digit, list rows with two or three candidate cells and write down their column sets. Three rows whose columns merge into exactly three is the pattern. Step through this real position to see it happen.

Practice

Find the Swordfish and clear its digit from the covered columns (or rows) outside the pattern.

Drill 1 of 29

Tap a cell, then the candidate digit you want to remove.