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. So you see that this guy gives you 60 just like it would from a logical physics perspective. From a pure mathematical perspective, it gives you zero if you use the formula. Now, one last thing I want to mention is that this definition of velocity is not actually correct.