How to Play

Fill the 9x9 grid so that every row, column, and 3x3 box contains the numbers 1-9 exactly once.

The starting numbers are fixed. Your job is to reason out the empty cells.

Controls

• Click a cell, then press a number button or use the keyboard keys 1-9.
• Use Backspace, Delete, 0, or C to clear the selected cell.
• Use the Arrow Keys to move around the grid.
• Press H for a hint on the selected empty cell.
• Press N to start a new puzzle.

A Good Solving Routine

1. Scan rows and columns for places where only one number can fit.
2. Check each 3x3 box and look for missing numbers.
3. Use elimination: if a number already appears in the same row, column, or box, it cannot go in the selected cell.
4. Slow down before guessing. Sudoku is most useful when each move has a reason.

Difficulty Guide

The game saves your current puzzle in the browser, so students can return later and continue.