Of course, science uses math to describe their theory. But math itself is an abstract theory and has nothing to do with describing or understanding real nature. So it doesn't fit into the science category, imho. E.g. I think I would not expect a CAS like Maxima in the science category. Adding "Math & " or " & Math" and then we could add Kig, too, couldn't we?
Probably we misunderstand ech other because of the meaning of "science". I mean that math is not a natural science, but of course it is a science in a more general sense. If science is understood in the more general way commonly, then we don't need to add math in the title.