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The Basic Layout of a Sudoku Puzzle
Before you become a champion sudoku solver, you will have to become familiar with the style of this puzzle and some of the terminology used.
Look at the basic puzzle presented below. You will see that it is composed of nine rows and nine columns each with nine squares in them. These eighty one squares are also divided up into three by three boxes. Some squares are filled in already. These numbers are referred to as the givens. The rest of the boxes are blank and will be referred to as empty cells. To solve this puzzle you must fill in each of these empty cells with a number from 1-9.  The One Rule of Sudoku
There is only one rule of sudoku, and every answer can be deduced based on this rule.
In each row, column, and three by three box fill in a number from 1-9 once and only once. Using this rule and the numbers given, you can deduce all the missing cells in the puzzle. There is no need to use any math, just deduction and elimination.  Simple Solving Methods
There are two very basic methods used to solve almost every sudoku puzzle. The first is done by eliminating
the possibility of one number from being in eight of the nine cells in a row, column, or three by three box.
If you can eliminate eight of the cells as possibilities then the number you are trying to find must be in the ninth cell.
To illustrate this, see the puzzle on the next page. We are going to find where the missing 1 must be in the top row by eliminating eight of the cells in the top leaving the cell that must contain the 1. As you can see, four of the cells can be eliminated as choices because they already contain a given number. Also every cell in the second box can be eliminated because that box already contains a 1. In the third box there is only one empty cell in the top row; however that can be eliminated because that column already contains a 1. So the only box left is where the 1 in the first row goes. And For My Second Trick…
The other way to fill in cells is to eliminate all possible numbers but one from a single cell. To illustrate this trick, we will consider the empty cell in the bottom left corner of the puzzle.
First by looking at the other numbers in the bottom left three by three box we know that the missing cell cannot be a 1, 3, 6, or 8. Now look in the column that contains the cell in question. Because there is a 2 and 4 in the column, we can eliminate them as possibilities for the bottom left cell. Finally, look at the bottom row. In this row we find a 7 and a 9. So that means that the only number left that can be the answer for the bottom left cell is 5. Let’s finish this puzzle!
Now that you know the one rule of sudoku and have two methods for filling in cells under your belt, let’s finish this puzzle we have been working on. Here is a hint. Look for a row, column, or three by three box with only one or two numbers missing. That is the easiest spot to start filling in more cells.
Fill in all the empty cells in any order you want. You can never solve a sudoku by starting on one side and working all the way through it. You will always have to jump around the puzzle filling in cells where you can. The more cells you fill, the more clues you will have to solve the remaining cells. Flip to the next page to see the finished puzzle. How Do I Know If I Solved the Puzzle Correctly?
Each sudoku puzzle has only one solution; there is only one number that will correctly fill each blank cell to complete the puzzle. If you fill in each spot without violating the one rule of sudoku then you have finished it correctly. You will also be able to fill in each space using logic and reasoning. No math or guessing is needed. If you get stuck, a good guess may help, but there was a way to solve the puzzle that you missed without the guess.
Good luck with the rest of the book and have fun! |
