Arrangement Check
A combination has to fit the cells, not just the total: if every combination containing this digit leaves some other cell in the run with nothing it can take, the digit is impossible here. Two or three combinations to weigh.
How it works
- 1Three cells sum to 8, and only two combinations reach it: 1+2+5 and 1+3+4.
- 2Each right-hand cell heads a 3-in-two down run, whose only combination is 1+2 — so between them they must supply exactly a 1 and a 2.
- 31+3+4 offers those two cells a single 1 and nothing else they can take, so it cannot be dealt out at all.
- 4Only 1+2+5 survives, so the left cell is 5. Two combinations to weigh is the narrow case, and the cheapest form of this technique.
- Cells that establish the pattern
- Where the conclusion lands
- Digit ruled out