An easy way to begin is first to generate the numbers that will provide the solution. The only requirement for this is that each row and column contains all the numbers from 1 to n (for an n×n puzzle). The cages and operations can then be added to create the final puzzle. Sometimes it may be necessary, during cage and operation selection, to modify the numbers in the grid slightly. These n × n grids of numbers with no duplicates in rows or columns are called “Latin squares”, and a great deal is known about them. For small grids, like the 4 × 4 grids that will be used for the first puzzles, they are fairly easy to generate, just by trial and error. But there are some easy ways to generate such squares totally mechanically in such a way that the resulting squares seem somewhat random. Note that once you have a Latin square, you can make another by rearranging the rows in any way, and then rearranging the columns in any way. Another way to make a new Latin square from an old one is to take any 1-to-1 function mapping 1 · · ·n to 1 · · ·n and applying that function to all the elements in an existing Latin square. There are 24 rearrangements of the rows, 24 rearrangements of the columns, and 24 suitable mappings, so just using these techniques, a single initial Latin square can have up to 24 × 24 × 24 = 13824 modifications. (A lot of these modifications yield the same Latin square; in fact, of the 4 × 4 variety, there are only 576 different examples.) So you can start with any Kenken puzzle, apply some of the transformations above, and get one that looks completely different with almost no effort. Also note that you can start with one that is very regular and modify it as explained above. Here is an easy beginning 4 × 4 Latin square, and the same pattern can be used to generate a starting Latin square of any size: