Maybe I'll do it like this. Maybe I'll do it T for thing. Thing 1, thing 2, thing 3, all the way to thing k. How many different ways can you order it? Thing 1 can be in k different positions. Thing 2 will be in k minus 1 positions. Then all the way down to the last one is only going to have one position. This is going to be k times k minus 1 times k minus 2, all the way down to 1.