Sudoku is a numbers puzzle game where the objective is to logically arrange numbers on a 9×9 grid. The playing board consists of a square board with nine rows, nine columns and nine 3×3 squares identified by darkened lines on the main playing board. The puzzle begins with some numbers already given on the grid and the challenge is to determine, through logical deduction, the remaining numbers. To complete the puzzle each square is given one number from a range of 1-9 and no number can be repeated in any row, column or square.
How do I start playing?|
Select a box on the grid without a number already in it and determine which numbers 1-9 can be a possible solution for that box and make a small notation in the box to keep track of it. Look at the row, column and square around the box you are trying to solve and eliminate any numbers that already exist. The remaining numbers are possibilities for that box and should be what you noted. If only one number remaining then you have solved the answer for that box. If there are multiple possibilities then move on to another box. Repeat this process as many times as necessary to discover as many answers as possible on the board.
“Eliminate all other factors, and the one which remains must be the truth.” – Sherlock Holmes
When you do find an answer you then need to look at what clues you now have to eliminate options in the boxes you have already taken notes on. Starting with your newly discovered answer look at the row, column and square associated with your find. If you have taken notes in any of these boxes erase that number you found as a possible option from the notes of any of these boxes. For example, If you have determined that the answer to a box is 4 and the a box in that row has a note saying 1,4 & 7 are possible answers then you would eliminate 4 as an option only leaving 1 & 7 as possibilities. If you discover other answers to the puzzle along the way continue searching the rows, columns and squares of each number you find in the puzzle. Often fining one answer leads to discovering several others. The most basic strategy in solving a Sudoku puzzles is to continue repeating the above steps until the puzzle is solved.
What can I do to make solving these puzzles easier?
First, look over the entire puzzle if any row, column or square has all but one number already given then the answer must be the missing number in the sequence. You should do this in the beginning when starting the puzzle and continue to look for these eight out of nine sequences while solving the puzzle.
A second technique to make things easier is to select you starting points well. When you begin to take notes you can start at any point in the puzzle. You can go left to right top to bottom or any other way that you may feel will bring you the answers you’re looking for. However, since taking notes may become the most daunting park of solving the puzzle you may want to minimize how much notes you have to take. One tip to do this is to always look at the longest chains of known numbers first. For example if a row has 6 out of 9 numbers already given then there can only be 3 possible answers in that row. Compare the possible answers in row with the known numbers in the associated columns and squares to further reduce the number of possibilities. By doing this you increase the chance of finding the answer or reducing the possibilities to no more than two answers.
One final tip I have for beginners is to continuously audit yourself as you go. The earlier in the puzzle solving process you make a mistake the harder it becomes to correct it. A quick way to audit yourself is to look at each row column and square as you solve them. It is very easy and only takes a second to run down the numbers and say “1,2,3,4,5,6,7,8,9 yup there all there”, then it is to track down the mistake at the end. One mistake will result in a chain of mistakes as you progress through the puzzle.
How do I know I’m making progress with my puzzle?
To work through the puzzle systematically and have a sense as to my progress I find it helpful to break the puzzle down into three phases. The first phase is “low hanging fruit”. These are the numbers you can find with very little effort. These include sequences that have only 1 or 2 missing numbers or those answers that just pop out at you. Second is what I call the “Hump”. You need to start using logical deduction to eliminate possibilities and figure out the right answers.
Typically finding the correct answers becomes increasingly more difficult as you progress through the puzzle. Finally, you will “Autopilot to the finish”. At some point you will be over the hump and the remaining answer will be self-fulfilling. Each time you find an answer it will eliminate 1 of 2 possibilities in another box therefore revealing the next answer. This will continue allowing you to quickly complete the puzzle. The real challenge in Sudoku is the piece in the middle which is overcoming the “Hump”. As you gain proficiency in the game you will progress through the puzzle fairly quickly only slowing down around the top of the hump.
Are all the puzzles this easy?
Sudoku comes in a varying degree of difficulties. This difficulty is achieved in the puzzle by reducing the numbers given at the start, removing certain sequences that give you the “low hanging fruit” and denying you any clues in finding one or more numbers all together. For example the puzzle may only start you with one “2”, “4” and “8” on the board at the start making it difficult to determine where any of these numbers fall elsewhere in the puzzle until you solve for the other numbers first.
Sudoku although a simple puzzle will challenge your logic and reasoning skills. These puzzles offer you a varying degree of difficulty. Some of the more difficult puzzles may even require skill beyond what’s laid out here. You can also add your own degree of difficulty to the puzzle. Try to see how fast you can complete the puzzle or try solving it without taking any notes. Yes, with the right combination of techniques you can solve even the most difficult puzzle without taking any notes. If you follow along, I will break these techniques down for you in future posts.
May all your puzzles be challenging and worth of your time!