Techniques · Easy
Naked single
A naked single is a cell with one digit left. The row, the column, or the box has already used the other eight, so the last digit is the one that goes in.
You can see it without writing every candidate. If eight different digits already sit in the cell's row, column, and box, the missing digit is placed. That is the whole of an Easy puzzle here.
When it shows up
Easy puzzles on this site are singles only. Quick puzzles are too, limited to hidden singles inside a box. Every harder level ends in singles once the tougher step has opened them.
All 495 NYT Easy puzzles in the archive are 38 clues and never need anything beyond singles.
See it on a real puzzle
The marks are the candidates left when this is the next step in the solve. Step through it: the pattern, what leaves, and what that forces.
See the pattern
Look at this cell.