Strategies for Sudoku

Its been a while since the Japanese number game Sudoku has implanted itself firmly in the minds of puzzle-players everywhere, challenging their problem-solving skills and providing endless hours of sometimes frustrating entertainment. Many have simply attacked the puzzles with pencil and eraser in hand, developing their own methods and strategies for solving the creative Sudoku grids. Who would have thought that the task of filling in numbers on a simple 9×9 grid would prove so challenging? Well, if you’ve already played the game, then you are aware of the single but rigid rule that turns an ordinary grid of numbers into a strictly regimented puzzle, as within each of the grid’s nine rows, columns and 3×3 blocks, the numbers 1 through 9 can appear only once. Not so simple anymore, is it?

And thus the game of Sudoku will either cause you to focus your complete mental efforts upon the page until all numbers are filled in, at which point you will be consumed by a wonderful feeling of satisfaction, or you will throw your pencil and puzzle across the room, vowing never again to waste your time on such meaningless, maddening puzzles.

There are in fact a number of Sudoku strategies and tips to help make the challenge a bit easier. Some areas of the Sudoku puzzle will be relatively simple to solve, but ultimately, you will come to a section of the grid where simple guesswork needs to be applied. For exactly this reason, you should always use a pencil and eraser. Not even the Sudoku professionals are above using a pencil.

Utilizing a pencil will allow you to plug in numbers and examine the results, and then erase if need be, as is often the case.

Starting in a 3×3 grid with the largest amount of numbers already pre-filled, examine the other numbers that appear along the rows and columns adjacent to the remaining empty squares of the grid. Alongside the margins of the paper, write down those numbers as well as the numbers in the 3×3 grid itself. If you are lucky, you will find that the remaining empty squares can only be filled in by one or two numbers, and then either guesswork or moving on to the next grid and applying the same technique will help produce the correct results.

Once one 3×3 grid has been completed, you may find that the strategy has made completing remaining grids, rows and columns somewhat easier, as numbers that can be utilized in adjacent empty squares are substantially narrowed down.

In situations where the answer doesn’t seem so clear, one tip is to start writing down possible numbers in the margins next to the empty squares. The strategy is to eliminate numbers already in the 3×3 grid first, then the numbers that correspond to the same row and column as the empty square. Often, you will find only one number remaining. In cases where the the solution could still be two numbers or more, the strategy is to examine the adjacent rows and columns and see what numbers exist there as well.

For example, if you have a choice of placing a ‘1’ or a ‘2’ in an empty box, then check the adjacent columns and rows next to other empty boxes in the 3×3 grid to see if they already contain a ‘1’ or a ‘2’. Keeping in mind that each number can only appear once in each row, column, and 3×3 grid, this strategy should help you logically conclude which number should be placed where.

As stated before, despite the presence of tips and strategies, guesswork is still a large factor of Sudoku, so don’t be discouraged if one strategy does not immediately produce favorable results.

If you find you have made an error, rather than try to untangle the puzzle one number at a time, another tip is to erase much of the puzzle and begin filling in numbers again, as this may prove reasonably faster.

Realistically, the most important strategy is to simply use logic. If it is not obvious what number should go in a box, then as you continue to work on a cube, either by guesswork or by filling in other obvious cubes, then you will gradually narrow down possibilities when you see the relation of the numbers to other areas of the puzzle.

Another good strategy is to try to first complete the easy 3×3 grids (grids where the bulk of the numbers have already been pre-filled) and from there, a complete row or column. This will help to substantially narrow down the numerical possibilities for other empty squares.

But once again, the key strategy, the most important tip, is simple logic and guesswork. It is usually mathematically impossible to complete the Sudoku puzzle without guesswork, so don’t waste your time looking for one concrete strategy that will enable you to complete Sudoku effortlessly. It doesn’t exist.

Countless books have already been written explaining Sudoku strategies and tips, but the comprehensive explanations and clever nicknames for particular strategies can often be more confusing than the Sudoku itself.