are you sure that it isn't kg x M/s? I don't know any useful aplication that would be kilograms per meters per second. anyways, if it is kg/ (m/s), then you would multiply it by 1/(3600/1000). if it is meters on top, you would multiply it by 1000/3600
so kg/(m x s)?
pretty much what you do, whatever side of the / the meters or seconds are on, you multiply the opposite side by 1000 or 3600, respectivley, one of my answers were wrong before, because they end up being the same thing.