3
8
4
6
2
9
1
7
5
4
3
7
6
5
8
1
3
4
7
1
8
3
2
4
6
8
6
5
6
2
4
8
7
7
5
8
2
2
7
5
6
7

This Sudoku Puzzle has 21 steps and it is solved using Locked Candidates Type 1 (Pointing), Locked Candidates Type 2 (Claiming), Naked Triple, Hidden Pair, Hidden Single, Uniqueness Test 4, undefined, Naked Single, Uniqueness Test 3, Give Up techniques.

Naked Single Explanation
Hidden Single Explanation
Hidden Pair Explanation
Locked Candidates Explanation
Locked Candidates Explanation
Try To Solve This Puzzle

Solution Steps:

  1. Locked Candidates Type 1 (Pointing): 2 in b3 => r3c45<>2
  2. Locked Candidates Type 1 (Pointing): 9 in b4 => r789c2<>9
  3. Locked Candidates Type 1 (Pointing): 1 in b6 => r79c7<>1
  4. Locked Candidates Type 2 (Claiming): 4 in r8 => r7c45,r9c45<>4
  5. Locked Candidates Type 2 (Claiming): 5 in c6 => r4c45,r5c45,r6c45<>5
  6. Naked Triple: 3,4,9 in r9c178 => r9c245<>3, r9c459<>9
  7. Locked Candidates Type 2 (Claiming): 3 in r9 => r7c7<>3
  8. Hidden Pair: 2,4 in r4c45 => r4c45<>3, r4c45<>8, r4c45<>9
  9. Row 4 / Column 6 → 8 (Hidden Single)
  10. Row 6 / Column 6 → 5 (Hidden Single)
  11. Locked Candidates Type 1 (Pointing): 3 in b5 => r6c7<>3
  12. Uniqueness Test 4: 5/9 in r4c27,r5c27 => r45c7<>9
  13. Uniqueness Test 4: 4/9 in r7c17,r9c17 => r79c7<>9
  14. W-Wing: 6/9 in r1c8,r4c9 connected by 9 in r36c7 => r3c9,r4c8<>6
  15. Row 4 / Column 9 → 6 (Hidden Single)
  16. Row 1 / Column 8 → 6 (Hidden Single)
  17. Locked Candidates Type 1 (Pointing): 9 in b3 => r3c456<>9
  18. Row 3 / Column 6 → 3 (Naked Single)
  19. Uniqueness Test 3: 6/8 in r3c45,r7c45 => r9c45<>1
  20. Uniqueness Test 4: 2/9 in r3c79,r7c79 => r7c9<>9
  21. Give Up: Don't know how to proceed!
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