Sudoku
Sudoku is another one of the most common puzzles you will come across during your time at HOL. Now, you might be thinking, "Hold on! I thought you said PUZZLES. Why are there numbers? This better not be math!" Fear not, it's not math, though there is simple counting (only to the number 9!) involved.
Sudoku is based off the 18th century Swiss "Latin Squares", and evolved until it became the number puzzle we know in 1895 France. It wasn't until 1984 though when it came to Japan and became Sudoku. Sudoku is short for a longer expression in Japanese – “Sūji wa dokushin ni kagiru” – which means, “the digits are limited to one occurrence.” Over the years there have been many alterations to change the difficulty of the puzzle, but here are three of the most common.
Sudoku is based off the 18th century Swiss "Latin Squares", and evolved until it became the number puzzle we know in 1895 France. It wasn't until 1984 though when it came to Japan and became Sudoku. Sudoku is short for a longer expression in Japanese – “Sūji wa dokushin ni kagiru” – which means, “the digits are limited to one occurrence.” Over the years there have been many alterations to change the difficulty of the puzzle, but here are three of the most common.
Standard Sudoku
This is the standard version of Sudoku. It is a square grid made of 9 little 3x3 squares, 9 rows, and 9 columns. The object is simply to have the numbers 1 through 9 occur only once in each 3x3 square, column and row.
How to solve: There are multiple ways to solve sudokus. First, decide if you want to start with squares, rows or columns. Then, try to fill out the number 1 in all of whichever you picked. After you've done as much as you can, move on to 2, then 3, etc. Once you've finished with 9, go to either one of the choices you didn't pick (squares, columns rows) and start over. Finally, do the one you have done. After that, go through each 3x3 square and see what blanks you have left. It helps to make little notes in the squares what they could possibly be. Make special note for numbers that can only be in certain squares. For example, say there are two squares in a 3x3 square that can only be 5 and 6. You may not know which one is 5 and which one is 6 yet, but you know that since other numbers can't be in those squares 5 and 6 have to be there so they won't be in the other squares. Where to practice: Sudoku How to make: First, make your grid. Draw one big square, divide that into 9 equal sized squares, and divide those into 9 squares. If you want to make sure the lines are perfect without spending a lot of time on it, you can find blank grids online. Next, fill the grid with 1 through 9 in each little 3x3 square starting with the top row. Make sure that there are none of the same numbers in each row. Then do the first column, again, making sure none of them are in the same row. Then do the second row, and finally the last row. After you have a complete grid, make a copy. This is your solution. Then erase the numbers to get a pattern you like. The more numbers you erase, the harder your puzzle will be. Once you are satisfied with how your puzzle looks, try to solve it. You want to make sure you left enough numbers for it to be solvable. If you can't get the solution, add a few numbers back in until you have enough to solve it. |
Visual Sudoku
Visual Sudoku is essentially the same thing as standard sudoku, except it uses pictures (generally to fit a theme) or letters to spell a word instead of numbers. You can only have one of each image in each row, column and 3x3 box.
How to solve: Some people find the pictures confusing and make it easier by assigning a number (1 through 9) to each image or letter. For example, in this picture the pear could be 1, the banana 2, the avocado 3, etc. Then you can solve it the same as you would a standard sudoku. How to make: The easiest way to solve this is to first make a standard sudoku puzzle. Before you do anything else, make sure your puzzle is actually solvable. You don't want to waste time replacing numbers with pictures only to find out your puzzle is impossible. Then, find 9 different pictures, usually to fit a theme. Remember, they are tiny pictures, so try to make them all different colors so if someone can't figure out what the picture is they can at least go by the colors. Then replace all of the 1's with one image, all of the 2's with the second image, etc, until all of the numbers have been replaced with your nine image. An important thing to remember is that you must have AT LEAST one of each image in your grid, since the solver has no way of knowing what the images are without you telling them (unlike in a standard sudoku where they know it has to be 1 through 9). Make sure you don't accidentally replace a number with the wrong picture. |
Killer Sudoku
Killer Sudoku is much trickier than regular sudoku while at the same time being easier, especially since it often starts out with a completely blank grid. Not only can you have the numbers 1 through 9 appear only once in each row, column and 3x3 row, they can't be repeated in a colored group and the numbers must add up to the sum in each colored group. For example, in the top left square there are two orange squares. The numbers you put in there must equal six, so you know that 6 through 9 can't be in there since you need two numbers to equal six. Additionally, 3 also cannot be in there because then you would have two threes in the same column, box, and colored group. So you know those two blocks are either 1 and 5 or 2 and 4.
How to solve: The first thing you should do is look for single colored blocks, and numbered blocks that can only have one solution. For example, in the top middle square there are two pinks squares with a sum of four. Since 2 can't be used twice, you know that those two squares are 1 and 3. Make a mark that they are those numbers, so you know that they can't be in any other blocks in that column or 3x3 square. You can figure out which is which after you have narrowed other ones down. Then, start solving it as you would a standard sudoku, bearing in mind the color of each block you are making notes in. Where to practice: Killer Sudoku How to make: Just like the Visual Sudoku, it is easiest to start out with making a standard sudoku. Next, create little groups with all the numbers. Try to give a few clues, like a pair that equals 4 or 17, since there are only 2 numbers you can add from 1 to 9 that will get either of those numbers. Next, color in the background of your groups different colors to help people keep the groups straight. For this type of sudoku, you don't have to leave any numbers because the groups should be sufficient for them to solve the puzzle. Once again, make sure your puzzle is solvable. It's helpful to ask a friend or two to try to solve your puzzles, just in case. |
Sources