Surface Triple
Two overlapping groups of runs differ by three cells — subtracting their clue totals ties those three digits together, ruling out any that can't be completed.
How it works
- 1The down clues cover the tinted block for 4 + 7 = 11; the across clues cover it plus the row's last three cells for 4 + 31 = 35.
- 2So those three cells total 35 − 11 = 24.
- 3Three different digits reaching 24: the two biggest are 9 and 8, so the smallest of the three can be no less than 24 − 17 = 7.
- 4A 5 anywhere among them is impossible. Strike it from all three.
- Cells that establish the pattern
- Where the conclusion lands
- Digit ruled out