Sudoku puzzles designed by reputable sources have exactly one unique logical solution. Guessing a number creates a butterfly effect of errors that usually ruins the puzzle later on, forcing you to restart.
"I didn't write that," Thorne whispered. His handwriting was messy, distinct. The title was printed in a sharp, jagged serif.
When easy scanning no longer reveals answers, you must transition to advanced deductive reasoning. Naked Pairs and Triples
If he put a '4' there, it contradicted the '2' he had placed earlier. But he knew the '2' was right. He felt it. The geometry of the puzzle demanded it.
: A strategy used to solve difficult puzzles by establishing a chain of strong and weak links between candidates to eliminate possibilities from specific cells. The 45 Rule
The puzzle was rated 'Expert'. Thorne exhaled a plume of steam from his cup. He scanned the rows. The logic usually flowed like water. Find the naked single, clear the pairs, scan the boxes.
Each horizontal row must contain the numbers 1 through 9 exactly once.
Hard Level Tip: Look for (three cells containing combinations of the same three numbers) or Naked Quads to significantly reduce candidates. 3. Hidden Pairs and Triples
