Sudoku Tips and Tricks


Sudoku Lingo

  • The Sudoku board is a 9x9 grid split up into 9 boxes:


  • On this page, a "space" will refer to any of the 81 small squares, and a "box" will be one of the nine larger 3x3 squares (numbered for reference).
  • Columns are the series of spaces that run up and down, while rows are the spaces that run left and right.

10 Tips for Sudoku

  1. If you're not sure where to start, brush up on the rules. Read Mahalo's guide to How to Play Sudoku for the rules of the game.
  2. Scan for repeated numbers. Any time a certain number appears multiple times in the puzzle, it is a good chance that it may lead you toward a solution.
    • If there is a 7 in boxes 1 and 3, you've canceled out two rows (6 total spaces) in box 2 that you know cannot hold a 7.
    • If there is also a 7 in, say, box 8, you've also narrowed down a column in box 2 that it cannot appear in.
    • Cross-reference where numbers appear across multiple boxes/columns/rows to eliminate potential spaces.
    • The more numbers you fill in, the more you are able to narrow down.
    • (Creative Commons photo by Eduardo Mueses)
      (Creative Commons photo by Eduardo Mueses)
  3. If you feel stuck, focus on just rows, columns, or boxes for a while. Sometimes you may find yourself scanning all over the puzzle while not getting anywhere in solving it. Try just focusing on rows for a while, or look only for clues in the columns.
  4. Change your row/column/box perspective. Often you'll find yourself agonizing over a particular space in a column without realizing that you already have 8 or 9 spaces of the row filled in. If you're getting nowhere in one place, look elsewhere.
  5. Move to a new area of the puzzle. If you feel like you can't go any further in the lower right hand corner, start looking for solutions in the upper left. Staring at a new part of the puzzle can be refreshing, and a breakthrough in one area of the grid can lead to solutions in others.
  6. Write down number possibilities with a pencil. If you've narrowed down a spot to only a couple digits, write them both down for a reference. Then you won't have to memorize all the possibilities and it will help give you a visual reference while working the puzzle out.
  7. Write every possible number in every empty space.
    • First, write all nine digits in each blank space (you can also use dots as explained in the Sudoku Wikipedia article).
    • When a number is eliminated from a given space, erase it. When only one number remains, that is the answer.
    • If a number appears as a possibility in only one space of any box, row, or column (even if it's not the final number remaining in said space), it is the answer.
    • If any box/row/column contains two spaces with matching pairs of numbers (like in this Howstuffworks example in which they show two spaces in the row containing only the possibilities of 5 and 6), those two numbers will definitely be in those spaces, although you don't know in which order. Therefore, you can eliminate the possibility of those numbers from any other space in that box/row/column.
  8. Write down all possibilities in a row, column, or box. If you don't want to go through the entire puzzle and fill in the possible digits, just use the above method in a single row/column/box to finish it out using the same logic.
  9. Take your best guess. If you still feel stuck, try taking a stab at guessing which number goes in a space.
    • This should only really be used if you've narrowed the space down to 2 possible digits—if you find a duplicate as you continue the puzzle, you'll know it must be the other possibility.
  10. Play every day. Now that you know some of the tricks for solving Sudoku, take a crack at a puzzle daily. The best way to get better at anything is to practice!

Have any more great tips for Sudoku? Post your tips to the discussion board or email them to Evan: EvanB at mahalo dot com.

Resources for Sudoku Tips and Tricks