Naked Pairs

Naked pairs are your first intermediate technique. They don't place numbers directly — instead, they eliminate candidates, which opens the door for other techniques to work.

What is a Naked Pair?

A naked pair is when two cells in the same unit (row, column, or box) contain exactly the same two candidates and nothing else.

Example: Two cells that both show only [3,7] form a naked pair.

The pair is called "naked" because the two candidates are fully visible — there are no other candidates hiding in those cells.

Visual Example

Before elimination:

After elimination:

The Logic Explained

Think about it step by step:

1. Cells A and B can only contain 3 or 7
2. One of them will be 3, the other will be 7
3. We don't know which is which yet
4. But we DO know that 3 and 7 are taken by these two cells

The result: No other cell in the row can have 3 or 7. They're "claimed" by the pair!

Where to Look

Naked pairs can exist in any unit:

In a Row

In a Column

The same logic works vertically. If two cells in a column both have [5,8], eliminate 5 and 8 from other cells in that column.

In a Box

Double Coverage

The best naked pairs affect multiple units at once!

If a naked pair in a box also shares a row or column, you can eliminate from both:

• Eliminate from other cells in the box
• AND eliminate from other cells in the shared row/column

How to Find Naked Pairs

Method 1: Look for Small Cells

1. Scan for cells with only 2 candidates
2. When you find one, look for an identical cell in the same unit
3. If found, you have a naked pair!

Method 2: Systematic Scanning

1. Pick a unit (start with boxes — they're easiest to see)
2. List all cells with exactly 2 candidates
3. Check if any two match

Method 3: Candidate Focus

1. Pick a pair of numbers (like 3 and 7)
2. Look for two cells that have ONLY those two numbers
3. Check if they share a unit

The Elimination Process

Once you find a naked pair:

1. Identify the shared unit(s) — row, column, box, or multiple
2. Check each other cell in that unit — does it have either candidate?
3. Remove those candidates — cross them off
4. Check for singles — did any cell become a single?
5. Look for new patterns — the elimination might reveal more pairs!

What the Pair Affects

Important: The naked pair eliminates from all cells in the shared unit (row, column, or box).

The rule is simple: If cells A and B form a naked pair in a row, eliminate from ALL other cells in that row. Same for columns and boxes.

Common Mistakes

Mistake 1: Eliminating from the pair cells

• NEVER remove candidates from the pair cells themselves
• They need to keep their [3,7] — that's the whole point!

Mistake 2: Missing a unit

• A cell might share a row AND a box with the pair
• You get to eliminate from both!

Mistake 3: Wrong candidates

• Only eliminate the pair's candidates (3 and 7 in our example)
• Don't remove other numbers

Mistake 4: Cells aren't identical

• [3,7] and [3,7,9] do NOT form a naked pair
• Both cells must have EXACTLY the same candidates

Mistake 5: Not following up

• After eliminating, check for new singles immediately
• The elimination might solve cells!

Naked Pairs vs Hidden Pairs

Both are equally powerful — they're just found differently.

When Naked Pairs Appear

• Easy puzzles: Rarely needed
• Medium puzzles: Occasionally useful
• Hard puzzles: Essential technique
• Expert puzzles: You'll use many naked pairs

Practice Exercises

Try to find the naked pair in each example:

Exercise 1:

Exercise 2:

What's Next?

Once you master naked pairs:

• Naked Triples — Same idea with three cells and three candidates
• Naked Quads — Same idea with four cells and four candidates
• Hidden Pairs — The reverse: two candidates that can only go in two cells