How to Create & Solve a Sudoku
Sudoku is a logic puzzle made up of nine boxes of nine squares. Each square must be contain a numeral from 1 to 9, and no square, row or column can contain the same number twice. Sudoku puzzles can be challenging, but following a series of steps can help you understand how the puzzle works and come to a solution more efficiently. A good way to practice is by creating your own Sudoku puzzles, which you can customize from a difficulty standpoint.
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Instructions
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Create a nine-cell by nine-cell chart on a new spreadsheet. Randomly assign numbers 1 to 9 in each row of the sheet, ensuring that the number does not appear more than once in any row or column.
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Check for accuracy using the "sum" function. Each box, row and column should add up to 45. Format the sheet so each square is the same size and print this sheet as your answer key.
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Remove numbers from cells without changing their positions. In general, more missing numbers makes a more difficult puzzle. When you are satisfied with the number of blank squares, print out the puzzle to solve.
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Scan for rows and columns that are missing one number. Since each number, 1 to 9, is used only once in each row or column, the empty square should contain the only digit not yet in the row. Write this number in the square and continue this step for as many squares as possible.
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Start in one box of nine squares and figure out which digits are missing. Scan the rows and columns that pass through blank squares in the box you're working on. If a digit missing from the box is present in an adjoining row or column, the blank square cannot hold that number. For example, if 5 and 7 are the only numbers missing from the box and you see a 7 in a row connected to the blank square, the blank square can not contain the 7. It must contain the 5.
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Split the sheet in thirds horizontally. The top three rows make up three boxes of nine squares. Working on this section only, scan each box for like numbers. For example, if there is a 2 in the top row of the right box and a 2 in the bottom row of the center box, you can deduct that the other 2 belongs in the center row of the left box. Determine exact square placement in that row based on pre-filled squares and the location of other 2s in adjoining columns and rows. Continue this process for as many numbers as possible before moving to the next third of the puzzle.
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Split the sheet in thirds vertically, and scan each box for like numbers. Fill in digits based on placement of like numbers in adjacent columns and rows.
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Rotate between the solving steps as more digits are filled in. After completing portions of the puzzle using horizontal and vertical thirds, revert to scanning for boxes missing only one number.
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Tips & Warnings
An online puzzle generator can be a helpful tool for making and verifying puzzles.
You also can make your own puzzles by filling in a spreadsheet with the values of a completed Sudoku puzzle and removing digits to create a new puzzle with the same solution.
Use a pencil and eraser instead of a pen.
If you are unable to determine the exact number for a square but you are able to narrow it down to two digits, lightly pencil the two numbers in a corner of the square as a reminder. As you complete different areas of the puzzle, you will be able to figure out which digit belongs in the square.
References
Resources
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