Jellyfish
ExpertA jellyfish is the next fish after the swordfish: four rows where one digit’s places all fall in the same four columns. Those rows use up the digit in those columns, so the rest of the four columns can’t have it.
How to spot it
- Pick one digit and find rows where it has two to four places.
- Find four of them whose places, together, cover only four columns.
- Remove the digit from every other cell of those four columns.
Why it works
Four rows need the digit once each, in four different columns, and they only have those four columns. Each column gets its digit from them.
Example
2
1
7
5
9
4
5
8
1
2
3
4
9
2
5
1
9
5
2
7
1
6
1
7
2
8
2
1
5
9
1
9
2
3
7
2
3
1
8
9
5
3
5
9
2
1
Look at the 6s in row 1, row 2, row 6, and row 9.
Common mistakes
- Letting the four rows cover a fifth column.
- Searching for it before X-wings and swordfish, which are much more common.