Naked Pair
Two cells in a house sharing the same two candidates lock those digits away from the rest.
How it works
- 1Find two cells in one house whose candidates are the same pair, say {3,8}.
- 2Between them they use up both 3 and 8 — in some order, but certainly both.
- 3No other cell in that house can be 3 or 8, so strike both digits everywhere else in it.