In how many different way can 8 riders be matched up with 8 horses
The first rider could be with any of 8 horses.
the second rider could be with any of the remaining 7 horses
etc
so 8*7*6*5*4*3*2*1 = 8! =
$${\mathtt{8}}{!} = {\mathtt{40\,320}}$$
my goodness, that is a lot of ways :/
64 combinations