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Sudoku #8 — the solutions

The three Sudoku boards from October 8, 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

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

The solution

1 9 4 | 6 7 3 | 2 8 5
2 6 8 | 9 5 4 | 1 3 7
5 3 7 | 2 1 8 | 9 6 4
------+-------+------
8 7 2 | 1 3 9 | 5 4 6
6 4 5 | 7 8 2 | 3 9 1
3 1 9 | 5 4 6 | 7 2 8
------+-------+------
9 5 3 | 8 6 1 | 4 7 2
4 8 1 | 3 2 7 | 6 5 9
7 2 6 | 4 9 5 | 8 1 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. 45 steps; yours need not match, and any order that never guesses ends on the same grid.

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

Medium — 28 digits given

Beyond singles, this board asks for a pointing line (2 times).

The board

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

The solution

3 6 9 | 5 7 2 | 8 1 4
2 8 7 | 9 1 4 | 3 5 6
4 5 1 | 6 3 8 | 2 9 7
------+-------+------
9 4 6 | 8 2 7 | 1 3 5
8 3 5 | 4 6 1 | 9 7 2
1 7 2 | 3 9 5 | 6 4 8
------+-------+------
5 2 4 | 1 8 9 | 7 6 3
7 1 3 | 2 4 6 | 5 8 9
6 9 8 | 7 5 3 | 4 2 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. 55 steps; yours need not match, and any order that never guesses ends on the same grid.

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

Hard — 30 digits given

Beyond singles, this board asks for a pointing line, a claimed box and an XY-wing.

The board

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

The solution

1 3 4 | 5 7 9 | 8 2 6
8 5 2 | 1 3 6 | 4 7 9
9 7 6 | 4 2 8 | 1 3 5
------+-------+------
6 9 8 | 7 4 5 | 3 1 2
5 2 3 | 8 9 1 | 7 6 4
4 1 7 | 3 6 2 | 9 5 8
------+-------+------
3 4 5 | 2 8 7 | 6 9 1
2 8 9 | 6 1 3 | 5 4 7
7 6 1 | 9 5 4 | 2 8 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. 54 steps; yours need not match, and any order that never guesses ends on the same grid.

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

Previous: Sudoku #7 (Wed, Oct 7)

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.