Naked Singles: The Foundation of Sudoku Solving

The Naked Single technique is the most basic and essential strategy in sudoku. It's the first technique every player should master, as it forms the foundation for all other solving methods.

What is a Naked Single?

A naked single occurs when a cell can only contain one possible number. This happens when all other digits (1-9) are already present in the cell's row, column, or 3×3 box.

How to Identify Naked Singles

Method 1: Visual Scanning

Look at each empty cell and mentally check:

1. Which numbers are in the same row?
2. Which numbers are in the same column?
3. Which numbers are in the same 3×3 box?

If 8 out of 9 digits are already used, the remaining digit is your answer!

Method 2: Using Notes

If you're using our Notes feature:

1. Write all possible candidates (1-9) for the cell
2. Cross out numbers that appear in the same row, column, or box
3. If only one number remains, you've found a naked single

Example

Consider this scenario:

Row contains: 1, 2, 3, 4, 5, 6, 7, 8
Column contains: 2, 3, 4, 5, 6, 7, 8, 9
Box contains: 1, 2, 3, 4, 5, 6, 7, 8

For the empty cell at the intersection:

• The row is missing only 9
• Therefore, this cell must be 9

This is a naked single!

Using Super Sudoku's Features

Auto-Generated Notes

Enable "Show auto generated notes" in settings to automatically see candidate numbers for empty cells. This makes spotting naked singles much easier.

Hint System

If you're stuck, select a cell and press the Hint button (or press 'H'). The game will fill in a naked single if one exists.

Conflict Detection

Turn on "Highlight conflicts" to ensure you don't accidentally create duplicate numbers in rows, columns, or boxes.

Practice Tips

1. Start systematically: Scan the entire grid row by row
2. Focus on constrained areas: Look for rows/columns/boxes with many filled cells
3. Use keyboard shortcuts: Press 'N' to toggle notes mode quickly
4. Build muscle memory: With practice, you'll spot naked singles instantly

Common Mistakes to Avoid

• Forgetting to check the box: Always verify all three constraints (row, column, AND box)
• Missing numbers: Double-check your elimination - it's easy to overlook a digit
• Rushing: Take your time, especially when learning

Beyond Naked Singles

Once you're comfortable with naked singles, you can explore:

• Hidden Singles: When a number can only go in one cell within a row/column/box
• Naked Pairs: When two cells in a unit can only contain the same two numbers
• Pointing Pairs: Using box-line interactions to eliminate candidates

Mastering naked singles will make these advanced techniques much easier to understand!

Try It Now

Open a puzzle in Super Sudoku and practice:

1. Enable "Show auto generated notes" in Settings
2. Start with an Easy puzzle
3. Look for cells with only one candidate number
4. Fill them in and watch the puzzle progress!

Happy solving!