Sandwich
A cell between two equal numbers is always kept — rejecting it would force both neighbors to stay, and they'd duplicate each other.
How it works
- 1The 8 sits between two 3s.
- 2If the 8 were rejected, both 3s would have to stay (rejected cells can't touch) — but two kept 3s in one row breaks the duplicate rule.
- 3So the 8 is kept, whatever its value.
- Kept
- Cells that establish the pattern
- Where the conclusion lands