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. In the example where we had 3 heads in 5 flips, this was 3 times 2 all the way down to 1. 3 times 2 times 1. Is there a simpler way that we can write this?