How to Solve a Sudoku Puzzle Step by Step

Learn the basic strategies and techniques to solve sudoku puzzles from beginner to intermediate level.

  1. Understanding the Basic Rules. Every sudoku puzzle is a 9x9 grid divided into nine 3x3 boxes. The goal is to fill every empty cell with numbers 1 through 9. Each row, column, and 3x3 box must contain all nine numbers exactly once. Start by examining the given numbers already filled in - these are your clues to solving the puzzle.
  2. Start with the Easy Wins. Look for cells where only one number can possibly fit. Scan each row, column, and 3x3 box to see what numbers are missing. If a cell can only contain one possible number based on what's already in its row, column, and box, fill it in right away. These easy fills will give you more clues for the harder cells.
  3. Use the Elimination Method. For each empty cell, write small pencil marks showing all the possible numbers that could go there. Cross out possibilities as you fill in other cells nearby. When you've eliminated all but one possibility for a cell, that's your answer. This method helps you keep track of your thinking and spot patterns.
  4. Look for Naked Singles and Hidden Singles. A naked single is a cell with only one possible number left after elimination. A hidden single is when a number can only go in one place within a row, column, or box, even if that cell has other pencil marks. Regularly scan for both types - they're your most reliable solving tools.
  5. Work Section by Section. Focus on one 3x3 box, row, or column at a time rather than jumping around randomly. Complete as much as you can in one section before moving to another. This systematic approach helps you spot patterns and makes fewer mistakes than scattered solving.
  6. When You Get Stuck. If you can't find any obvious moves, step back and double-check your work. Look for numbers that appear frequently across the puzzle - these often provide new clues. Try focusing on a number that appears 6-7 times already and see where the remaining ones must go. Take breaks if you're frustrated - fresh eyes often spot solutions.