How to Beat Sudoku

Many newspapers print daily Sudoku puzzles.

Sudoku is a puzzle played on a nine-by-nine grid, which contains certain numbers already filled in. The goal of the game is to fill in the remaining numbers so that each column, row and block contains the numbers 1 to 9 only one time. Sudoku, originally called Number Place, was first published in the 1970s by a "New York" magazine titled Math Puzzles and Logic Problems. It did not gain popularity until a Japanese publisher started printing its own version in 1984. Although Sudoku is often associated with math, it actually involves no calculations. Beginners can quickly pick up a Sudoku puzzle and learn how to solve it.

Things You'll Need

• Pencil
• Eraser

Instructions

1. Start at the top left inner block and note which numbers are missing. Take the lowest missing number and note each cell it can possibly fit without having that same digit in the same row, column or block. Fill in the number if there is only one cell for that digit. Use a very small digit in the corner of each appropriate cell if more than location is possible at this time. Repeat the same process for each missing number in the top left block. Repeat process for each of the remaining eight blocks in the Sudoku puzzle.

2. Return to the first block and check to see if any of the newly filled in numbers make more solutions possible. Erase or cross out any of the small digits indicating solutions that are no longer possible. Repeat for each of the remaining blocks.

3. Scan rows of three adjacent blocks to see if a certain number appears in two blocks. If so, note the block that still needs that number. Review that block and determine which cells that number can fit in. Use the same method to scan columns of three blocks. (See Reference 2).

4. Review the entire puzzle and fill in any remaining solutions. If a single cell can still accommodate more than one solution, test a single digit and attempt solving the remaining puzzle. If a problem arises, erase and test the next digit. Retry different digits until the puzzle is complete. Check the puzzle to make sure no row, column or block contains repeat digits.

Tips & Warnings

• Use a separate sheet of paper to mark possible solutions if you have large writing.

• All Sudoku puzzles follow the same format but range in difficulty from very simple to very difficult.

References

• "Mammoth Book of Sudoku"; Oceana; 2007
• Reader's Digest: Getting Started on Sudoku

Resources

• Reader's Digest: Surprising Advice on Solving Sudoku