This gives you 3600 plus negative canceled. So 3600 gives you 7200 divided by two and square root, that gives you 60 mph. So you see, once again, that the purpose of the route means square is to take away those negative signs and just give you the magnitude. And this becomes useful when you're talking about velocities. Because if a molecule is traveling with one velocity this way and another molecule is traveling with the same velocity but the direction the other way, you want to take those averages and you want those averages to give you a positive value, not zero. That's exactly why you use root mean square velocity.