0/4 lessons answered correctly on this browser. You can repeat any lesson.
Single candidate
Check the highlighted cell’s row, column and box. Which digit is missing?
What belongs in row 1, column 1?
These are original fixed exercises. Explanations use the same visible-candidate engine as classic Sudoku hints; no answer lookup supplies the deduction.
How to play Sudoku Solving Techniques
Learn by placing a digit in an original practice position. Start with a single candidate, then explore the only place for a digit, locked candidates and naked pairs. Each exercise lets you answer before opening its explanation.
- Choose a lesson and inspect the highlighted cell. White numbers are the fixed position; your answer appears in gold.
- Select the digit you think belongs there. An incorrect answer gives feedback and lets you try again without a penalty.
- Open the explanation to follow each visible-candidate deduction. For locked candidates and pairs, read the elimination before the final placement.
- A check mark records an answered lesson in this browser. You can revisit all examples, including ones you have already completed.
- Continue into classic Sudoku and use its progressive Hint, Explain and Apply controls to practice the same reasoning in a full puzzle.
A tip for your next game
Distinguish a cell with one candidate from a digit with one possible place in a unit. Both force an entry, but the second technique can work while that cell still has several candidates.
Common questions
Are these live puzzles or fixed lessons?
These are fixed original teaching positions with checked unique solutions. Full random and daily puzzles remain available in classic Sudoku.
Do the explanations use the hidden answer?
No. The visible-candidate engine derives the placements and elimination steps from the displayed position. Tests compare its deduction with the unique solution.
Does lesson completion prove mastery?
No. The local record only means you selected the correct answer in these exercises, including after viewing an explanation. Repeated practice in new puzzles builds experience.