EXTREMEPUZZLE BOOKS

Extreme Sudoku 1, puzzle 96: step-by-step solution

Step through the whole solution, or skip to the hard parts. Blue digits are placed by the walkthrough; red strike-through marks a candidate being ruled out.

Puzzle
Sudoku, number 96 of 150 in Extreme Sudoku 1
Difficulty
Expert 7 (expert and beyond), from the middle third of the book
Key technique
WXYZ-Wing
Hard steps
22 of 41 steps need an advanced or expert technique

Blue digits are placed by the walkthrough. Red strike-through marks a candidate being ruled out. Cells are named by row and column: R3C5 is row 3, column 5. Arrow keys step too.

The key technique: WXYZ-Wing

Four cells holding four digits between them, where only one digit is not confined. That digit is removed from cells that see all its copies.

Other advanced and expert techniques in this solve: ALS-XZ (×4), Empty Rectangle (×3), Nice Loops/AICs (×3), 2-String Kite (×2), Cell Forcing Chains, Coloring/Multi-coloring, Finned Fish, Skyscraper, W-Wing, XY-Chain.

Every move above the basics is listed on the sudoku techniques page, each with a one-sentence explanation and worked examples from the books.

The hard steps, in text (22)
  1. Step 5 · Empty Rectangle advanced
    Rules out 1 from R2C2.
  2. Step 6 · Empty Rectangle advanced
    Rules out 1 from R5C9.
  3. Step 7 · WXYZ-Wing expert
    Rules out 5 from R2C3.
  4. Step 8 · ALS-XZ expert
    Rules out 3 from R2C2.
  5. Step 9 · ALS-XZ expert
    Rules out 6 from R8C1.
  6. Step 10 · WXYZ-Wing expert
    Rules out 9 from R1C1.
  7. Step 11 · Nice Loops/AICs expert
    Rules out 1 from R9C2.
  8. Step 12 · Nice Loops/AICs expert
    Rules out 6 from R9C2.
  9. Step 13 · Cell Forcing Chains expert
    Rules out 1 from R1C1.
  10. Step 15 · 2-String Kite advanced
    Rules out 1 from R2C9.
  11. Step 16 · Empty Rectangle advanced
    Rules out 1 from R9C9.
  12. Step 17 · Finned Fish expert
    Rules out 1 from R6C9.
  13. Step 18 · Nice Loops/AICs expert
    Rules out 1 from R2C3.
  14. Step 21 · Coloring/Multi-coloring expert
    Rules out 1 from R9C3.
  15. Step 22 · 2-String Kite advanced
    Rules out 1 from R5C8.
  16. Step 23 · WXYZ-Wing expert
    Rules out 5 from R6C8, R6C9.
  17. Step 24 · WXYZ-Wing expert
    Rules out 9 from R9C8, R9C9.
  18. Step 25 · ALS-XZ expert
    Rules out 5 from R9C1.
  19. Step 26 · ALS-XZ expert
    Rules out 1 from R6C8.
  20. Step 32 · Skyscraper advanced
    Rules out 5 from R4C3, R5C3, R8C2.
  21. Step 36 · W-Wing advanced
    Rules out 2 from R3C7, R5C9.
  22. Step 38 · XY-Chain expert
    Rules out 3 from R1C9, R3C2.

The book

Classic 9×9 sudoku with the warm-up taken out. Every grid sits at the top of the expert range or beyond it, and the book ramps from hard to brutal.

150 puzzles. Expert and beyond. Puzzles by M. J. Bailey. Paperback, 5 × 8 in, 196 pages, £9.99 / $11.99. Every solution in the book carries a QR code to its own walkthrough, so you can check one step without seeing the whole answer.

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More step-by-step solutions: Extreme Killer Sudoku 1 · Extreme Sudoku 2 · Extreme Killer Sudoku 2 · Extreme Sudoku 3 · Extreme Killer Sudoku 3.