How to Spot Naked Pairs
Naked Pair (also called a "naked pair" or "locked pair") is the first real wall at the intermediate level. You find two cells that share the exact same two candidate numbers, then eliminate those numbers from other cells in the same row, column, or block.
How to Find Them
Organize Candidates First
Use the memo feature to write candidate numbers for each cell. Naked Pairs cannot be seen without candidates.
Look for Pairs in the Same Unit
Find cells that have exactly 2 candidates. Then check if another cell in the same row, column, or block has the same 2 candidates.
Eliminate After Finding
The 2 numbers in the pair can be eliminated from all other cells in the same row, column, or block.
Common Example
If cells A and B both have candidates {2,5}, then no other cell in that unit can contain 2 or 5.
Naked Pair vs. Hidden Pair
Naked Pair = "these 2 cells have ONLY these 2 candidates." Hidden Pair = "these 2 numbers can ONLY go in these 2 cells." The perspective is opposite — be careful not to confuse them.