Hidden Singles Sudoku Technique
Learn how hidden singles work, when to scan for them, and how to practice them on a live Sudoku board.
Hidden singles are one of the most important Sudoku patterns because they teach players to scan a whole row, column, or box instead of staring at one cell in isolation.
What is Hidden Singles?
A hidden single happens when one number can only go in one place inside a row, column, or 3x3 box.
The cell may still look open, but every rival square in that unit quietly rejects the digit.
When to use it
Use it after easy singles dry up and the board still has several half-open units.
It is especially strong when one digit already appears many times and only a few placements remain.
Step-by-step example
Step 1
Pick one digit and one unit
Instead of scanning everything, track one missing digit through a single row, column, or box.
Step 2
Rule out the rival cells
If a candidate conflicts with the row, column, or box of that square, remove it.
Step 3
Place the digit when only one square survives
The move is not obvious from the cell alone, but it is forced by the unit.
Practice Hidden Singles on a live board
This live board lets you practice the technique immediately while the idea is still fresh.
54% complete
44/81 correct · 44 filled
Interactive practice board
Use Explain Move to study the next logical step without auto-filling the answer.
Instant validation
Mark wrong placements as you enter them.
Reveal mistakes
Toggle visible mistake highlights when you want a cleanup pass.
Hints
0
Win rate
0%
Streak
0
Pick a cell to start.
Related techniques and next steps
Technique pages work best as a cluster. Once one concept clicks, the player should always have a relevant next page to open.