Year 9: Challenge - Sudoku

This cheat-sheet helps you solve Sudoku puzzles, a logic-based number-placement game. In Sudoku, you need to fill a 9x9 grid with digits from 1 to 9 such that each digit appears only once in each row, column, and 3x3 subgrid.

Key Rules

• Rows: Each row must contain the digits 1-9 exactly once.
• Columns: Each column must also contain the digits 1-9 exactly once.
• 3x3 Subgrids (Blocks): The grid is divided into nine 3x3 subgrids. Each subgrid must also contain the digits 1-9 exactly once.

Basic Strategies

• Scanning: Look for digits that appear frequently in rows, columns, or subgrids. This will narrow down the possible locations for that digit.
• Marking Candidates: In each empty cell, write down the possible digits that can be placed there, based on the rules.
• Hidden Singles: If a digit can only appear in one cell within a row, column, or subgrid, then that must be the digit for that cell.
• Naked Singles: If a cell has only one possible candidate remaining, then that is the digit for that cell.

Tips

• Start with the easiest sections of the puzzle (those with the most clues).
• Don't be afraid to erase and try different possibilities.
• Practice makes perfect!