How to Solve Sudoku: Naked Single

A cell's column, row and box together hold 8 different digits. It must be the one digit left.

Also called a sole candidate. On Puzzle Lounge it appears from Easy up.

See it step by step

  1. Look at row 6, column 7
  2. This cell's column, row and box (digits here cannot go in this cell)
  3. Present: 1, 2, 3, 4, 5, 6, 7 and 9 (8 of the digits 1 to 9)
  4. Only 8 is missing (this cell's notes come down to one)
  5. So this cell is 8

This is Easy No.3, partly solved.

Solve this puzzle →Print and solve →

How to find it

  1. Pick an empty cell.
  2. Count every digit in that cell's column, row and box.
  3. If 8 different digits are there, the missing one is the answer for that cell.

Things to watch

  • A digit that appears in both the column and the row counts once.
  • If you have notes written, this is a cell with only one note.
Read the full explanation

If the column, row and box a cell sees already hold 8 different digits from 1 to 9, only the one digit left can go there.

Suppose a cell's column has 1, 3 and 7, its row has 2, 5 and 9, and its box has 4 and 6. That makes 8 different digits.

Of 1 to 9, only 8 is missing. Only 8 can go in this cell.

The column, row and box of row 6, column 7 hold 1, 2, 3, 4, 5, 6, 7 and 9. Of 1 to 9, only 8 is missing, so this cell is 8.

Other techniques

Hidden SinglePointingClaimingHidden PairHidden TripleCage Combinations (Killer)Rule of 45 (Killer)Naked PairNaked TripleX-WingXY-WingSwordfishSkyscraper2-String KiteXYZ-WingW-WingJellyfish

For the basics and how to use notes, see how to solve sudoku, with tips. If you get stuck, the game's hints guide you step by step, starting with where to look.

Solve sudoku (free, no download) →