Kenken is a numbers puzzle game like sudoku, and both are meant to be good for sharpening your arithmetic skills and your logic. You have a square grid (typically 4x4, 6x6 or 8x8) to be filled with numbers such that each number is unique in its own row and colum. The boxes in the grid are also partitioned into "cages"; often defined by a common thick border line. The numbers in a cage must produce the total number specified in the cage when the specified operation is applied to all the numbers in the cage. Here's an empty kenken board:
In the bottom row, for instance, we have 2 cages: one composed of 3 numbers (one for each box) whose sum (because the given operation is addition) is 6, the other cage has only one box containing number 4. No operation needs to be specified for a cage with only one box. So filling first the single-box cages, we have:
Now looking at the rightmost column, there's a 2-box cage with total 2 and operation division. Since we have a 4x4 grid (meaning, the only possible numbers are 1, 2, 3, 4), only 2 and 1 can be used to fill this 2-box cage. That leaves 3 as the only number for the remaining box at the top of the rightmost column.
Now that we've filled that upper-right-most box with 3, it's cage therefore has 3x1x3 = 9 (which we could actually deduce even without knowledge about the other boxes).
The topmost row has only one box left and it can only be 4. So the cage for that box (2 by division) contains 4 and 2 because 4/2=2.
Now we can go more quickly. The cage on the right (2 by division, 2/1=2) will have 1 in the upper box and 2 in the lower. The cage in the third row (7 by addition, 4+3=7) will have 3 in the left box and 4 on the right box.
Thus we can now easily deduce the complete solution. The cage in the first column (3 by subtraction, 4-1=3) will have 4 on the upper box and 1 on the lower box. The last cage at the bottom will have 3+1+2=6.
Yoohoo! We have just solved our first Kenken puzzle!