Extreme Killer Sudoku 3, puzzle 60: 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.
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: Remote Pairs
A chain of cells that all hold the same pair alternates between the two digits. Cells that see both ends of an odd-length link cannot hold either digit.
Other advanced and expert techniques in this solve: Multi-Sector Locking (×2), Advanced Innies (3+ sectors), Forcing Chains, Skyscraper, XY-Wing.
Every move above the basics is listed on the killer sudoku techniques page, each with a one-sentence explanation and worked examples from the books.
The hard steps, in text (7)
- Step 9 · Multi-Sector Locking advanced
Rules out 9 from R1C9, R2C9, R3C9, R6C7; 7 from R7C8, R8C8; 8 from R7C8, R8C8. - Step 16 · Advanced Innies (3+ sectors) advanced
Places 2 in R1C6, 6 in R8C4 and rules out 2 from R1C1, R1C2, R1C3, R1C4 and 11 more; 6 from R1C4, R2C4, R3C4, R5C4 and 9 more; 5 from R1C5, R2C5, R5C3, R8C5 and 1 more. - Step 66 · Skyscraper advanced
Rules out 8 from R8C2. - Step 67 · Remote Pairs expert
Rules out 7 from R8C2. - Step 82 · Multi-Sector Locking advanced
Rules out 7 from R1C3. - Step 83 · XY-Wing advanced
Rules out 8 from R1C1. - Step 87 · Forcing Chains expert
Rules out 7 from R1C1.
The book
Volume three: 150 new killers, none repeated from books 1 or 2. No starting digits, just cages and their totals, ramping from hard to brutal.
150 new 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.
Try a free sample puzzle (PDF) · prints on A4 or US Letter
More step-by-step solutions: Extreme Sudoku 1 · Extreme Killer Sudoku 1 · Extreme Sudoku 2 · Extreme Killer Sudoku 2 · Extreme Sudoku 3.