Kakuro: sum 7 in 3 cells
A sum of 7 in 3 cells has exactly one digit set: 1+2+4.
| Combination | Digit set |
|---|---|
| 1 + 2 + 4 | 124 |
What this tells you
- Unique. There is only one possibility, so as soon as you see this clue on a run of 3 cells you know the digits 1, 2, 4 go in it. Only their order is open, and crossing runs usually decide that.
- Digits that can never appear: 3, 5, 6, 7, 8, 9. You can remove them from every cell of the run.
Related sums
The digits left out of each combination form a combination for the mirror run: sum 38 in 6 cells.
Sum 7 is also possible in 2 cells.