Rows and columns are referred to with row number first, followed by the column number:
4,5 is row 4, column 5
2,8 is row 2, column 8
Boxes are numbered 1 – 9 in reading order: 123 456 789
Guessing
Try not to guess. Until you have progressed to the touch and diabolical puzzles, guessing is not only totally unnecessary, but will lead you up paths that can make the puzzle virtually unsolvable. Simple logic is all that is required for gentle and moderate puzzles. Most puzzles that are rated easy to hard will require some sort of analysis.
Starting the Game
To solve Sudoku puzzles you will need to use logic. You need to ask yourself questions like “if a 1 is in this cell, will it go in this column?” or “if a 9 is already in this row, can a 9 go in this cell?” To make a start, look at each of the regions in the grid below and see which cells are empty, at the same time checking that cell’s column and row for a missing number. In this example, look at region 9. There is no 8 in the region, but there is an 8 in column 7 and in column 8. The only place for an 8 is in column 9, and in this box the only cell available is in row 9. So put an 8 in that cell. Once you have done this you have solved your first number.
Continuing to think about 8, there is no 8 in region 1, but you can see an 8 in rows 1 and 2. So, in region 1, an 8 can only go in row 3, but there are 2 cells available. Make a note of this by penciling in a small 8l in both cells. Later, when you have found the position of the 8 in regions 4 or 7, you will be able to disprove one of your 8’s in region 1. The more methodical that you are about solving your first Sudoku puzzles the better you will become at understanding the logic behind how you solve them. Take time when glancing through regions so that you don’t scan through and miss an obvious number that you can place in a cell. Missing one number can set you back on how fast you solve the puzzle.
You have been looking at region 9. As you can see, there is a 2 in regions 7 and 8, but none in region 9. The 2’s in row 8 and row 9 mean the only place for a 2 in region 9 appears to be in row 7, and as there is already a 2 in column 8, there is only one cell left in that region for a 2 to go. You can enter the 2 for region 9 at 7,7.
As stated earlier, the more time you take in learning which strategy works best for certain puzzles the faster you will catch on to the logic behind the puzzle. Once you enter the number 2 in region 8 you will be ready to eliminate other numbers from other regions. Sudoku is all about filling in cells one by one by the process of elimination.
There is a similar situation with the 4’s in regions 4 and 5, but here the outcome is not so definite. Together with the 4 in column 7 these 4’s eliminate all the available squares in region 6 apart from two. Pencil a small 4 in these two cells. Later on, one or other of your pencil marks will be proved or disproved.
Having proved the 2 in region 9 earlier, check to see if this helps you to solve anything else. For example, the 2 in region 3 shows where the 2 should go in region 6; it can only go in column 9, where there are two available squares. As you have not yet proved the position of the 4, one of the cells may be either a 4 or a 2.
It’s time for you to solve a number on your own. Take a look at region 8 and see where the number 7 should go. Continue to solve the more obvious numbers. There will come a point when you will need to change your strategy. The following puzzling solving tips will provide you with some schemes to solve the complete Sudoku puzzle. Some solvers base their entire strategy on schemes that they use consistently to solve certain puzzles.
Continue to Chapter 7...
