Easy technique · Technique Academy

Naked Single

A naked single is a cell with only one digit left that it could possibly hold. Everything else is ruled out by the digits already in its row, column and box.

Professor Cryptic, the owl who teaches in the app
Professor Cryptic is thinking

The reasoning

Why does the Naked Single work?

Look at an empty cell and cross off what its three neighbourhoods already contain. If one digit survives, it is the answer, and no cleverness was required.

A worked example

What does the Naked Single look like on a real board?

Naked Single worked exampleA sudoku board with pencil marks. The Naked Single uses R7C4 and digit 7 (row 7, column 4 and box 8). The move places 7 in R7C4.134714781257845794579612592357912357991671257857342567125673467467574579125983567947379145678945782589257925789521793793789786379484796234579345794572591235792537789184168161689435215875691568917178917896457814578325912589
The move places 7 in R7C4. Digit 7, row 7, column 4 and box 8.
  • The cell that decides

Make it stick

How can you practise the Naked Single?

The Technique Academy in Cryptic gives every technique its own lesson and 5 practice boards that need exactly this move.

Get it onGoogle PlayPlay Cryptic on the web

Further reading: HoDoKu's page on this family of techniques.

HarderHidden Single