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Sudoku #22 — the solutions

The three Sudoku boards from October 22, 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

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

The solution

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

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

Medium — 30 digits given

Beyond singles, this board asks for a pointing line (3 times).

The board

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

The solution

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

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 3, column 2 is 3. 3 has only one place left in the top-left box.
  2. Row 1, column 2 is 4. 4 has only one place left in the top-left box.
  3. Row 2, column 5 is 9. 9 has only one place left in the top-center box.
  4. Row 1, column 8 is 1. 1 has only one place left in the top-right box.
  5. Row 6, column 7 is 4. 4 has only one place left in the middle-right box.
  6. Row 5, column 8 is 6. 6 has only one place left in the middle-right box.
  7. Row 9, column 2 is 6. 6 has only one place left in the bottom-left box.
  8. Row 7, column 8 is 8. 8 has only one place left in the bottom-right box.
  9. Row 1, column 9 is 2. 2 has only one place left in row 1.
  10. Row 1, column 7 is 9. 9 has only one place left in the top-right box.
  11. Row 8, column 7 is 7. Nothing but 7 is left for this cell.
  12. Row 9, column 1 is 7. 7 has only one place left in row 9.
  13. Row 7, column 1 is 4. 4 has only one place left in the bottom-left box.
  14. Row 7, column 2 is 9. 9 has only one place left in the bottom-left box.
  15. Row 9, column 8 is 4. 4 has only one place left in row 9.
  16. Row 9, column 3 is 5. 5 has only one place left in row 9.
  17. Row 7, column 4 is 5. 5 has only one place left in row 7.
  18. In the top-left box, 2 can only sit in row 2, so it leaves the rest of that row.
  19. In the top-left box, 8 can only sit in row 2, so it leaves the rest of that row.
  20. Row 3, column 7 is 8. 8 has only one place left in column 7.
  21. Row 2, column 7 is 6. 6 has only one place left in the top-right box.
  22. In the top-right box, 7 can only sit in row 3, so it leaves the rest of that row.
  23. Row 3, column 4 is 6. Nothing but 6 is left for this cell.
  24. Row 8, column 6 is 6. 6 has only one place left in the bottom-center box.
  25. Row 8, column 5 is 4. 4 has only one place left in the bottom-center box.
  26. Row 3, column 6 is 4. 4 has only one place left in the top-center box.
  27. Row 3, column 5 is 2. 2 has only one place left in the top-center box.
  28. Row 4, column 6 is 2. 2 has only one place left in the center box.
  29. Row 5, column 2 is 2. 2 has only one place left in the middle-left box.
  30. Row 2, column 3 is 2. 2 has only one place left in the top-left box.
  31. Row 2, column 1 is 8. 8 has only one place left in the top-left box.
  32. Row 2, column 2 is 5. 5 has only one place left in the top-left box.
  33. Row 6, column 1 is 5. 5 has only one place left in the middle-left box.
  34. Row 6, column 2 is 7. 7 has only one place left in the middle-left box.
  35. Row 4, column 3 is 8. 8 has only one place left in the middle-left box.
  36. Row 4, column 1 is 9. 9 has only one place left in the middle-left box.
  37. Row 5, column 1 is 3. 3 has only one place left in the middle-left box.
  38. Row 6, column 4 is 3. 3 has only one place left in the center box.
  39. Row 5, column 5 is 7. 7 has only one place left in the center box.
  40. Row 4, column 9 is 3. 3 has only one place left in the middle-right box.
  41. Row 4, column 8 is 7. 7 has only one place left in the middle-right box.
  42. Row 3, column 9 is 7. 7 has only one place left in the top-right box.
  43. Row 3, column 8 is 5. 5 has only one place left in the top-right box.
  44. Row 5, column 9 is 8. 8 has only one place left in the middle-right box.
  45. Row 6, column 9 is 9. 9 has only one place left in the middle-right box.
  46. Row 7, column 5 is 3. 3 has only one place left in the bottom-center box.
  47. Row 8, column 3 is 3. 3 has only one place left in the bottom-left box.
  48. Row 7, column 3 is 1. 1 has only one place left in the bottom-left box.
  49. Row 8, column 4 is 1. 1 has only one place left in the bottom-center box.
  50. Row 2, column 6 is 1. 1 has only one place left in the top-center box.
  51. Row 2, column 4 is 7. 7 has only one place left in the top-center box.
  52. Row 7, column 6 is 7. 7 has only one place left in the bottom-center box.
  53. Row 8, column 9 is 5. 5 has only one place left in the bottom-right box.
  54. Row 8, column 8 is 9. 9 has only one place left in the bottom-right box.

Hard — 28 digits given

Beyond singles, this board asks for a pointing line (3 times), a claimed box (2 times) and an XY-wing.

The board

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

The solution

5 6 7 | 3 1 4 | 9 8 2
2 8 4 | 9 6 5 | 7 3 1
3 9 1 | 7 2 8 | 5 4 6
------+-------+------
1 2 9 | 4 8 6 | 3 7 5
7 4 5 | 2 3 9 | 6 1 8
6 3 8 | 5 7 1 | 4 2 9
------+-------+------
9 5 3 | 1 4 2 | 8 6 7
4 1 6 | 8 9 7 | 2 5 3
8 7 2 | 6 5 3 | 1 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. 59 steps; yours need not match, and any order that never guesses ends on the same grid.

  1. Row 2, column 2 is 8. 8 has only one place left in the top-left box.
  2. Row 1, column 8 is 8. 8 has only one place left in the top-right box.
  3. Row 6, column 1 is 6. 6 has only one place left in the middle-left box.
  4. Row 7, column 6 is 2. 2 has only one place left in the bottom-center box.
  5. Row 8, column 5 is 9. 9 has only one place left in the bottom-center box.
  6. Row 9, column 5 is 5. 5 has only one place left in the bottom-center box.
  7. Row 9, column 4 is 6. 6 has only one place left in the bottom-center box.
  8. Row 2, column 5 is 6. 6 has only one place left in the top-center box.
  9. Row 9, column 6 is 3. 3 has only one place left in the bottom-center box.
  10. Row 8, column 6 is 7. 7 has only one place left in the bottom-center box.
  11. Row 1, column 1 is 5. 5 has only one place left in row 1.
  12. Row 7, column 2 is 5. 5 has only one place left in the bottom-left box.
  13. Row 8, column 8 is 5. 5 has only one place left in the bottom-right box.
  14. Row 4, column 9 is 5. 5 has only one place left in the middle-right box.
  15. Row 3, column 7 is 5. 5 has only one place left in the top-right box.
  16. Row 5, column 9 is 8. 8 has only one place left in the middle-right box.
  17. Row 4, column 5 is 8. 8 has only one place left in the center box.
  18. Row 7, column 7 is 8. 8 has only one place left in the bottom-right box.
  19. Row 2, column 4 is 9. 9 has only one place left in row 2.
  20. Row 8, column 1 is 4. 4 has only one place left in row 8.
  21. Row 8, column 3 is 6. 6 has only one place left in row 8.
  22. Row 9, column 2 is 7. Nothing but 7 is left for this cell.
  23. In the top-center box, 1 can only sit in row 1, so it leaves the rest of that row.
  24. Row 3, column 3 is 1. 1 has only one place left in the top-left box.
  25. In the top-right box, 4 can only sit in row 3, so it leaves the rest of that row.
  26. In the center box, 3 can only sit in column 5, so it leaves the rest of that column.
  27. In row 2, 7 can only sit inside the top-right box, so it leaves the rest of that box.
  28. In column 8, 1 can only sit inside the middle-right box, so it leaves the rest of that box.
  29. XY-wing: one of its two wings must be 9, so no cell that sees both can be.
  30. Row 4, column 3 is 9. 9 has only one place left in the middle-left box.
  31. Row 5, column 1 is 7. 7 has only one place left in the middle-left box.
  32. Row 1, column 3 is 7. 7 has only one place left in the top-left box.
  33. Row 3, column 4 is 7. 7 has only one place left in the top-center box.
  34. Row 1, column 4 is 3. 3 has only one place left in the top-center box.
  35. Row 1, column 6 is 4. 4 has only one place left in the top-center box.
  36. Row 1, column 5 is 1. 1 has only one place left in the top-center box.
  37. Row 6, column 6 is 1. 1 has only one place left in the center box.
  38. Row 4, column 4 is 4. 4 has only one place left in the center box.
  39. Row 6, column 5 is 7. 7 has only one place left in the center box.
  40. Row 5, column 5 is 3. 3 has only one place left in the center box.
  41. Row 6, column 2 is 3. 3 has only one place left in the middle-left box.
  42. Row 3, column 1 is 3. 3 has only one place left in the top-left box.
  43. Row 3, column 2 is 9. 9 has only one place left in the top-left box.
  44. Row 4, column 2 is 2. 2 has only one place left in the middle-left box.
  45. Row 5, column 2 is 4. 4 has only one place left in the middle-left box.
  46. Row 5, column 8 is 1. 1 has only one place left in the middle-right box.
  47. Row 6, column 8 is 2. 2 has only one place left in the middle-right box.
  48. Row 6, column 7 is 4. 4 has only one place left in the middle-right box.
  49. Row 4, column 8 is 7. 7 has only one place left in the middle-right box.
  50. Row 7, column 3 is 3. 3 has only one place left in the bottom-left box.
  51. Row 7, column 1 is 9. 9 has only one place left in the bottom-left box.
  52. Row 9, column 9 is 4. 4 has only one place left in the bottom-right box.
  53. Row 3, column 8 is 4. 4 has only one place left in the top-right box.
  54. Row 3, column 9 is 6. 6 has only one place left in the top-right box.
  55. Row 9, column 7 is 1. 1 has only one place left in the bottom-right box.
  56. Row 2, column 9 is 1. 1 has only one place left in the top-right box.
  57. Row 2, column 7 is 7. 7 has only one place left in the top-right box.
  58. Row 7, column 8 is 6. 6 has only one place left in the bottom-right box.
  59. Row 7, column 9 is 7. 7 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.