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this game has been occupying a good amount of my time the past couple days. it has been called “the new crossword puzzle,” but in all actuality, the game has been around for centuries in the far east. it exercises basic principles of logic and is fun to work on even in groups (nate and i did a few together). the basic principle is as follows:

Fill in the grid so that every row, every column, and every 3×3 box contains the digits 1 through 9.

pretty simple, isn’t it? luckily, there are easy, medium, and hard levels of game play, which helps quite a bit in easing you into what processes to use to reach the solution. i’ll explain a few of the processes to use which will get you started.

parental advisory: i created the example above by myself, and i only put in numbers that would help to explain a few of the techniques for solving the puzzle, so don’t try to complete this one at home. the black numbers are those that were in place from the beginning of a new game and the grey numbers are those that were “logiced” in to place. also, i have created a notation for easier identification of certain squares by listing the row letter and the column letter directly in a row. for instance, the square at row g and column B would be listed as gB. click on the image to see a larger one.

ex 1

looking at the top three rows (a, b, c), you will see three 7s, two black and one grey. since we know that there can only be one of each number in each row, column, and small box, we can use the two black 7s to find the grey one. there is already a 7 in the small box on the left and the small box in the middle, and those 7s are in row a and row c. we still need a 7 in the small box on the right but that 7 can’t be in row a or c, so it must be in row b. column G and H are already occupied, so by default, it must be aI.

wonderful! that was a simple example, but we got it figured out nonetheless. we shall continue on to something a little more complex.

ex 2

for this example we will focus primarily on the small box on the bottom left, but to determine the value of the empty box we must look elsewhere. finding the 2 in gE you can see that it rules out all possibility of any 2s to the right or left of it. unfortunately, there aren’t any other 2s in either box to the right or the left of it on different rows. there is, however, a two in the top left box and that rules out any two below it. using that, along with the all other spaces in the bottom left box being filled save one, we can deduce that the empty space (hC) must then be a 2.

ex 3

this example will concentrate almost exclusively on column E. if you look up and down it, you will see that there are only 2 spaces that are empty (eE and bE). counting all the numbers in that row, we notice that the only two remaining are 3 and 4. so, one of those empty spaces must be a 3 and the other a 4. upon closer inspection, you will see that there is already a 3 in the middle box, so the empty space in that same box in column E cannot be an 3. therefore, eE must be a 4 and bE must be a 3.

simple enough? there certainly more to the game than this, but this will certainly get you started. there are hundreds of books available at any bookstore, they are now appearing in newspapers, and plenty of free ones online. go now and play.