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Sudoku #42 — the solutions

The three Sudoku boards from November 11, 2026 — Easy, Medium and Hard — each with its solved grid and a path through it, step by step, that never needs a guess.

Easy — 36 digits given

Every cell falls to scanning: a digit with only one place left in a row, a column or a box.

The board

· 6 7 | 9 · · | · 5 ·
3 · · | · · 5 | · · ·
· · · | 1 7 6 | · 3 2
------+-------+------
8 3 · | 4 · 2 | 5 6 7
· · · | · · · | · · ·
5 9 6 | 8 · 7 | · 4 1
------+-------+------
4 7 · | 3 1 8 | · · ·
· · · | 7 · · | · · 4
· 5 · | · · 4 | 3 7 ·

The solution

2 6 7 | 9 4 3 | 1 5 8
3 1 4 | 2 8 5 | 7 9 6
9 8 5 | 1 7 6 | 4 3 2
------+-------+------
8 3 1 | 4 9 2 | 5 6 7
7 4 2 | 5 6 1 | 9 8 3
5 9 6 | 8 3 7 | 2 4 1
------+-------+------
4 7 9 | 3 1 8 | 6 2 5
6 2 3 | 7 5 9 | 8 1 4
1 5 8 | 6 2 4 | 3 7 9

A path through it

The order a solver takes — always the cheapest move left, so a pattern is only reached for when the singles run dry. 45 steps; yours need not match, and any order that never guesses ends on the same grid.

  1. Row 3, column 3 is 5. 5 has only one place left in the top-left box.
  2. Row 2, column 7 is 7. 7 has only one place left in the top-right box.
  3. Row 2, column 9 is 6. 6 has only one place left in the top-right box.
  4. Row 5, column 1 is 7. 7 has only one place left in the middle-left box.
  5. Row 5, column 6 is 1. 1 has only one place left in the center box.
  6. Row 4, column 3 is 1. 1 has only one place left in the middle-left box.
  7. Row 5, column 9 is 3. 3 has only one place left in the middle-right box.
  8. Row 6, column 5 is 3. 3 has only one place left in the center box.
  9. Row 1, column 6 is 3. 3 has only one place left in the top-center box.
  10. Row 8, column 3 is 3. 3 has only one place left in the bottom-left box.
  11. Row 8, column 5 is 5. 5 has only one place left in the bottom-center box.
  12. Row 5, column 4 is 5. 5 has only one place left in the center box.
  13. Row 5, column 5 is 6. 6 has only one place left in the center box.
  14. Row 4, column 5 is 9. 9 has only one place left in the center box.
  15. Row 9, column 4 is 6. 6 has only one place left in the bottom-center box.
  16. Row 8, column 1 is 6. 6 has only one place left in the bottom-left box.
  17. Row 9, column 5 is 2. 2 has only one place left in the bottom-center box.
  18. Row 2, column 4 is 2. 2 has only one place left in the top-center box.
  19. Row 1, column 1 is 2. 2 has only one place left in the top-left box.
  20. Row 2, column 2 is 1. 1 has only one place left in the top-left box.
  21. Row 1, column 7 is 1. 1 has only one place left in the top-right box.
  22. Row 3, column 7 is 4. 4 has only one place left in the top-right box.
  23. Row 2, column 3 is 4. 4 has only one place left in the top-left box.
  24. Row 3, column 2 is 8. 8 has only one place left in the top-left box.
  25. Row 3, column 1 is 9. 9 has only one place left in the top-left box.
  26. Row 1, column 5 is 4. 4 has only one place left in the top-center box.
  27. Row 2, column 5 is 8. 8 has only one place left in the top-center box.
  28. Row 1, column 9 is 8. 8 has only one place left in the top-right box.
  29. Row 2, column 8 is 9. 9 has only one place left in the top-right box.
  30. Row 5, column 2 is 4. 4 has only one place left in the middle-left box.
  31. Row 5, column 3 is 2. 2 has only one place left in the middle-left box.
  32. Row 6, column 7 is 2. 2 has only one place left in the middle-right box.
  33. Row 5, column 7 is 9. 9 has only one place left in the middle-right box.
  34. Row 5, column 8 is 8. 8 has only one place left in the middle-right box.
  35. Row 9, column 1 is 1. 1 has only one place left in the bottom-left box.
  36. Row 8, column 2 is 2. 2 has only one place left in the bottom-left box.
  37. Row 9, column 3 is 8. 8 has only one place left in the bottom-left box.
  38. Row 7, column 3 is 9. 9 has only one place left in the bottom-left box.
  39. Row 8, column 6 is 9. 9 has only one place left in the bottom-center box.
  40. Row 8, column 8 is 1. 1 has only one place left in the bottom-right box.
  41. Row 7, column 8 is 2. 2 has only one place left in the bottom-right box.
  42. Row 7, column 9 is 5. 5 has only one place left in the bottom-right box.
  43. Row 7, column 7 is 6. 6 has only one place left in the bottom-right box.
  44. Row 8, column 7 is 8. 8 has only one place left in the bottom-right box.
  45. Row 9, column 9 is 9. 9 has only one place left in the bottom-right box.

Medium — 28 digits given

Beyond singles, this board asks for a pointing line.

The board

· · · | · 7 1 | 2 4 ·
· · · | 5 · · | 3 · 7
· 1 · | · · · | · 5 ·
------+-------+------
· 9 · | · 2 · | 8 · ·
1 · · | 8 · 5 | · · 9
· · 5 | · 6 · | · 7 ·
------+-------+------
· 3 · | · · · | · 8 ·
4 · 6 | · · 8 | · · ·
· 5 8 | 6 1 · | · · ·

The solution

5 8 3 | 9 7 1 | 2 4 6
6 4 9 | 5 8 2 | 3 1 7
7 1 2 | 3 4 6 | 9 5 8
------+-------+------
3 9 4 | 1 2 7 | 8 6 5
1 6 7 | 8 3 5 | 4 2 9
8 2 5 | 4 6 9 | 1 7 3
------+-------+------
9 3 1 | 7 5 4 | 6 8 2
4 7 6 | 2 9 8 | 5 3 1
2 5 8 | 6 1 3 | 7 9 4

A path through it

The order a solver takes — always the cheapest move left, so a pattern is only reached for when the singles run dry. 54 steps; yours need not match, and any order that never guesses ends on the same grid.

  1. Row 1, column 1 is 5. 5 has only one place left in the top-left box.
  2. Row 2, column 8 is 1. 1 has only one place left in the top-right box.
  3. Row 3, column 7 is 9. 9 has only one place left in the top-right box.
  4. Row 4, column 9 is 5. 5 has only one place left in the middle-right box.
  5. Row 7, column 3 is 1. 1 has only one place left in the bottom-left box.
  6. Row 4, column 4 is 1. 1 has only one place left in row 4.
  7. Row 4, column 6 is 7. 7 has only one place left in the center box.
  8. Row 4, column 3 is 4. 4 has only one place left in row 4.
  9. Row 2, column 2 is 4. 4 has only one place left in the top-left box.
  10. In the top-right box, 6 can only sit in column 9, so it leaves the rest of that column.
  11. Row 7, column 7 is 6. 6 has only one place left in the bottom-right box.
  12. Row 8, column 7 is 5. 5 has only one place left in the bottom-right box.
  13. Row 7, column 5 is 5. 5 has only one place left in the bottom-center box.
  14. Row 8, column 9 is 1. 1 has only one place left in the bottom-right box.
  15. Row 6, column 7 is 1. 1 has only one place left in the middle-right box.
  16. Row 9, column 7 is 7. 7 has only one place left in the bottom-right box.
  17. Row 5, column 7 is 4. 4 has only one place left in column 7.
  18. Row 3, column 5 is 4. 4 has only one place left in column 5.
  19. Row 2, column 5 is 8. 8 has only one place left in the top-center box.
  20. Row 8, column 5 is 9. 9 has only one place left in column 5.
  21. Row 9, column 8 is 9. 9 has only one place left in the bottom-right box.
  22. Row 7, column 1 is 9. 9 has only one place left in the bottom-left box.
  23. Row 8, column 2 is 7. 7 has only one place left in the bottom-left box.
  24. Row 5, column 3 is 7. 7 has only one place left in the middle-left box.
  25. Row 3, column 1 is 7. 7 has only one place left in the top-left box.
  26. Row 1, column 2 is 8. 8 has only one place left in the top-left box.
  27. Row 2, column 1 is 6. 6 has only one place left in the top-left box.
  28. Row 3, column 6 is 6. 6 has only one place left in the top-center box.
  29. Row 1, column 9 is 6. 6 has only one place left in the top-right box.
  30. Row 3, column 9 is 8. 8 has only one place left in the top-right box.
  31. Row 5, column 2 is 6. 6 has only one place left in the middle-left box.
  32. Row 6, column 1 is 8. 8 has only one place left in the middle-left box.
  33. Row 6, column 2 is 2. 2 has only one place left in the middle-left box.
  34. Row 4, column 1 is 3. 3 has only one place left in the middle-left box.
  35. Row 5, column 8 is 2. 2 has only one place left in the middle-right box.
  36. Row 6, column 9 is 3. 3 has only one place left in the middle-right box.
  37. Row 5, column 5 is 3. 3 has only one place left in the center box.
  38. Row 4, column 8 is 6. 6 has only one place left in the middle-right box.
  39. Row 9, column 1 is 2. 2 has only one place left in the bottom-left box.
  40. Row 7, column 4 is 7. 7 has only one place left in the bottom-center box.
  41. Row 7, column 9 is 2. 2 has only one place left in the bottom-right box.
  42. Row 8, column 4 is 2. 2 has only one place left in the bottom-center box.
  43. Row 2, column 6 is 2. 2 has only one place left in the top-center box.
  44. Row 3, column 3 is 2. 2 has only one place left in the top-left box.
  45. Row 1, column 3 is 3. 3 has only one place left in the top-left box.
  46. Row 2, column 3 is 9. 9 has only one place left in the top-left box.
  47. Row 3, column 4 is 3. 3 has only one place left in the top-center box.
  48. Row 1, column 4 is 9. 9 has only one place left in the top-center box.
  49. Row 6, column 6 is 9. 9 has only one place left in the center box.
  50. Row 6, column 4 is 4. 4 has only one place left in the center box.
  51. Row 9, column 6 is 3. 3 has only one place left in the bottom-center box.
  52. Row 7, column 6 is 4. 4 has only one place left in the bottom-center box.
  53. Row 8, column 8 is 3. 3 has only one place left in the bottom-right box.
  54. Row 9, column 9 is 4. 4 has only one place left in the bottom-right box.

Hard — 29 digits given

Beyond singles, this board asks for an XY-wing.

The board

· · 7 | 2 · · | · 3 9
· · · | · · 9 | 2 · 8
· · · | · 4 · | · 1 5
------+-------+------
· 5 8 | · 9 · | · · ·
· 1 · | · 7 · | · 8 ·
· · · | · 1 · | 3 5 ·
------+-------+------
3 4 · | · 2 · | · · ·
7 · 5 | 9 · · | · · ·
6 2 · | · · 1 | 8 · ·

The solution

1 6 7 | 2 8 5 | 4 3 9
5 3 4 | 1 6 9 | 2 7 8
8 9 2 | 3 4 7 | 6 1 5
------+-------+------
2 5 8 | 4 9 3 | 7 6 1
4 1 3 | 5 7 6 | 9 8 2
9 7 6 | 8 1 2 | 3 5 4
------+-------+------
3 4 1 | 6 2 8 | 5 9 7
7 8 5 | 9 3 4 | 1 2 6
6 2 9 | 7 5 1 | 8 4 3

A path through it

The order a solver takes — always the cheapest move left, so a pattern is only reached for when the singles run dry. 53 steps; yours need not match, and any order that never guesses ends on the same grid.

  1. Row 2, column 4 is 1. 1 has only one place left in the top-center box.
  2. Row 1, column 1 is 1. 1 has only one place left in the top-left box.
  3. Row 2, column 1 is 5. 5 has only one place left in the top-left box.
  4. Row 2, column 3 is 4. 4 has only one place left in the top-left box.
  5. Row 1, column 7 is 4. 4 has only one place left in the top-right box.
  6. Row 5, column 3 is 3. 3 has only one place left in the middle-left box.
  7. Row 6, column 2 is 7. 7 has only one place left in the middle-left box.
  8. Row 6, column 3 is 6. 6 has only one place left in the middle-left box.
  9. Row 5, column 7 is 9. 9 has only one place left in the middle-right box.
  10. Row 6, column 1 is 9. 9 has only one place left in the middle-left box.
  11. Row 7, column 3 is 1. 1 has only one place left in the bottom-left box.
  12. Row 8, column 2 is 8. 8 has only one place left in the bottom-left box.
  13. Row 3, column 1 is 8. 8 has only one place left in the top-left box.
  14. Row 3, column 3 is 2. 2 has only one place left in the top-left box.
  15. Row 3, column 2 is 9. 9 has only one place left in the top-left box.
  16. Row 2, column 2 is 3. 3 has only one place left in the top-left box.
  17. Row 1, column 2 is 6. 6 has only one place left in the top-left box.
  18. Row 9, column 3 is 9. 9 has only one place left in the bottom-left box.
  19. Row 7, column 7 is 5. 5 has only one place left in the bottom-right box.
  20. Row 7, column 8 is 9. 9 has only one place left in the bottom-right box.
  21. Row 2, column 8 is 7. 7 has only one place left in row 2.
  22. Row 3, column 7 is 6. 6 has only one place left in the top-right box.
  23. Row 2, column 5 is 6. 6 has only one place left in the top-center box.
  24. Row 1, column 5 is 8. 8 has only one place left in column 5.
  25. Row 1, column 6 is 5. 5 has only one place left in the top-center box.
  26. Row 5, column 4 is 5. 5 has only one place left in the center box.
  27. Row 9, column 5 is 5. 5 has only one place left in the bottom-center box.
  28. Row 8, column 5 is 3. 3 has only one place left in column 5.
  29. Row 9, column 9 is 3. 3 has only one place left in the bottom-right box.
  30. Row 7, column 9 is 7. 7 has only one place left in the bottom-right box.
  31. Row 4, column 7 is 7. 7 has only one place left in the middle-right box.
  32. Row 4, column 9 is 1. 1 has only one place left in the middle-right box.
  33. Row 9, column 4 is 7. 7 has only one place left in the bottom-center box.
  34. Row 3, column 6 is 7. 7 has only one place left in the top-center box.
  35. Row 3, column 4 is 3. 3 has only one place left in the top-center box.
  36. Row 4, column 6 is 3. 3 has only one place left in the center box.
  37. Row 8, column 6 is 4. 4 has only one place left in the bottom-center box.
  38. Row 8, column 7 is 1. 1 has only one place left in the bottom-right box.
  39. Row 9, column 8 is 4. 4 has only one place left in the bottom-right box.
  40. XY-wing: one of its two wings must be 2, so no cell that sees both can be.
  41. Row 4, column 1 is 2. 2 has only one place left in the middle-left box.
  42. Row 5, column 1 is 4. 4 has only one place left in the middle-left box.
  43. Row 6, column 9 is 4. 4 has only one place left in the middle-right box.
  44. Row 4, column 4 is 4. 4 has only one place left in the center box.
  45. Row 5, column 6 is 6. 6 has only one place left in the center box.
  46. Row 6, column 6 is 2. 2 has only one place left in the center box.
  47. Row 6, column 4 is 8. 8 has only one place left in the center box.
  48. Row 5, column 9 is 2. 2 has only one place left in the middle-right box.
  49. Row 4, column 8 is 6. 6 has only one place left in the middle-right box.
  50. Row 7, column 4 is 6. 6 has only one place left in the bottom-center box.
  51. Row 7, column 6 is 8. 8 has only one place left in the bottom-center box.
  52. Row 8, column 8 is 2. 2 has only one place left in the bottom-right box.
  53. Row 8, column 9 is 6. 6 has only one place left in the bottom-right box.

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About Sudoku

Sudoku on Noggin is three boards a day, on the second shelf: every entry is checked at once, a hint fills the next cell a solver would and says why, and the first board finished is the day’s score, outside the daily line-up. How to play Sudoku, or play today’s.