4-cell killer cage summing to 21
11 combinations.
- Always present
- No digit is forced into this cage.
- Never present
- Every digit can appear in this cage.
Valid digit combinations
- 1389
- 1479
- 1569
- 1578
- 2379
- 2469
- 2478
- 2568
- 3459
- 3468
- 3567
How to use this in play
11 digit sets sum to 21 across 4 cells. Without other constraints this cage is loose; the value comes from pairing it with the cage's row, column, or box context — every digit ruled out elsewhere narrows which combinations remain.