Sudoku

Sudoku is a logic-based number-placement puzzle that has captivated puzzle enthusiasts worldwide. The objective is to fill a 9x9 grid with digits from 1 to 9 so that each column, each row, and each of the nine 3x3 subgrids (also called "boxes" or "regions") contains all of the digits from 1 to 9 exactly once.

The puzzle starts with some cells already filled in (called "givens"). Your task is to fill in the remaining cells using pure logic and deduction. No guessing is required! Sudoku puzzles can range from easy and quick to solve to extremely challenging puzzles that test even the most experienced solvers.

• Select a cell: Click on any empty cell to select it. Selected cells will be highlighted.
• Enter a number: Click on a number button (1-9) to place that number in the selected cell.
• Follow the rules: Each row, column, and 3x3 box must contain all digits 1-9 without repetition.
• Use Erase: Click the Erase button (or press Backspace) to clear a cell you've filled.
• Use Hint: Stuck? Click the Hint button to reveal a correct number in an empty cell.
• Check your progress: Click Check to see if your current entries are correct (incorrect entries will be highlighted).
• Complete the puzzle: Fill all cells correctly to win!

• Start with easy spots: Look for cells where only one number can possibly fit based on the current board state.
• Use pencil marks: In harder puzzles, note possible candidates in each cell to help with advanced techniques.
• Look for naked singles: If a cell has only one possible number, fill it in.
• Scan rows and columns: Check which numbers are already present in each row, column, and box to narrow down possibilities.
• Work systematically: Tackle one box at a time, filling in all obvious placements before moving on.
• Take breaks: Sometimes stepping away and returning later helps you spot patterns you missed.