Extreme Killer Sudoku 2, puzzle 63: 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: Coloring/Multi-coloring
Following one digit’s strong links, cells get two colours: one colour is true and the other is false. A cell that sees both colours cannot hold the digit.
Other advanced and expert techniques in this solve: 2-String Kite (×3), Forcing Chains, Multi-Sector Locking.
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 (6)
- Step 15 · Multi-Sector Locking advanced
Rules out 7 from R4C1, R5C1, R6C1, R7C6 and 3 more; 4 from R7C4, R7C5, R7C6, R8C6; 8 from R9C7. - Step 49 · Coloring/Multi-coloring expert
Rules out 6 from R6C3. - Step 55 · 2-String Kite advanced
Rules out 8 from R9C5. - Step 58 · 2-String Kite advanced
Rules out 8 from R2C3. - Step 59 · 2-String Kite advanced
Rules out 9 from R9C5. - Step 60 · Forcing Chains expert
Rules out 4 from R2C4, R3C4; 1 from R2C7, R3C4; 2 from R2C8, R3C1, R3C4, R3C5.
The book
Volume two: 150 new killers, none repeated from book 1. 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 Sudoku 3 · Extreme Killer Sudoku 3.