EXTREMEPUZZLE BOOKS

Extreme Killer Sudoku 3, puzzle 150: 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
Killer sudoku, number 150 of 150 in Extreme Killer Sudoku 3
Difficulty
Expert 2 (expert and beyond), from the final, hardest third of the book
Key technique
Remote Pairs
Hard steps
8 of 83 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: 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: Advanced Innies (3+ sectors), Empty Rectangle, Forcing Chains, Multi-Sector Locking, Skyscraper, Sue de Coq.

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 (8)
  1. Step 42 · Multi-Sector Locking advanced
    Rules out 2 from R4C5, R5C5; 1 from R6C5.
  2. Step 43 · Advanced Innies (3+ sectors) advanced
    Rules out 2 from R3C5, R6C5; 9 from R5C6, R6C6; 5 from R6C5.
  3. Step 57 · Empty Rectangle advanced
    Rules out 6 from R4C2.
  4. Step 59 · Remote Pairs expert
    Rules out 4 from R6C4, R8C1, R9C5; 9 from R6C4.
  5. Step 62 · Remote Pairs expert
    Rules out 1 from R5C2, R6C2, R8C1, R9C1; 6 from R5C2, R6C2, R8C1, R9C1.
  6. Step 73 · Forcing Chains expert
    Rules out 5 from R1C7.
  7. Step 77 · Sue de Coq advanced
    Rules out 1 from R6C6.
  8. Step 78 · Skyscraper advanced
    Rules out 1 from R7C2.

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.

On Amazon from 15 Dec About the book

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.