Lesson 7 · Solve safely
Common Sudoku Mistakes
Recognise guessing, missed conflicts, and unreliable notes before they derail a puzzle.
See the logic move
Use Next to reveal each reason. On the final step, tap the highlighted cell to complete the move yourself.
Guided solution reveal · Cell Candidates
Step 1 of 3
Focus
row 3, column 7 currently allows 1, 3, 4, 5, 7.
Ask about any cellTap a square on the board
Select an empty cell to see its legal candidates and why the other digits are blocked.
Why this works
- 1
row 3, column 7 currently allows 1, 3, 4, 5, 7.
- 2
Inspect R3C7 and then check its row, column, and 3x3 box.
What the board is showing
TargetThe cell currently being tested.R3C7
Relevant unitThe row, column, or box controlling this move.R3C2, R3C3, R3C8, R7C7
Explain it simply
Mistakes usually happen when we rush. A short three-way check keeps the board trustworthy.
Step by step
- Avoid guessing between two candidates.
- Recheck row, column, and box.
- Keep candidate notes current.
- Pause after each placement.
Quick check: What is the safest action when two candidates remain and neither is proven?
Leave both notes and continue solving elsewhere.
Turn logic into skill