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Sudoku #27 — the solutions

The three Sudoku boards from October 27, 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

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

The solution

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

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

Medium — 31 digits given

Beyond singles, this board asks for a claimed box (2 times).

The board

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

The solution

1 4 6 | 8 5 9 | 7 3 2
8 7 9 | 1 3 2 | 4 6 5
5 2 3 | 6 4 7 | 8 1 9
------+-------+------
7 6 4 | 3 9 5 | 1 2 8
9 5 8 | 2 1 6 | 3 4 7
2 3 1 | 7 8 4 | 5 9 6
------+-------+------
4 1 5 | 9 6 8 | 2 7 3
6 8 2 | 4 7 3 | 9 5 1
3 9 7 | 5 2 1 | 6 8 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. 52 steps; yours need not match, and any order that never guesses ends on the same grid.

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

Hard — 28 digits given

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

The board

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

The solution

2 6 8 | 5 3 7 | 4 9 1
9 4 1 | 2 6 8 | 7 3 5
7 3 5 | 9 1 4 | 8 2 6
------+-------+------
8 2 9 | 7 5 3 | 6 1 4
1 7 3 | 8 4 6 | 2 5 9
4 5 6 | 1 9 2 | 3 7 8
------+-------+------
3 1 7 | 4 8 9 | 5 6 2
6 9 4 | 3 2 5 | 1 8 7
5 8 2 | 6 7 1 | 9 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. 56 steps; yours need not match, and any order that never guesses ends on the same grid.

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