I was this girl! I LOVED math (except I called it "maths" because UK) all through elementary school, right up until the age of 14 where suddenly only boys were supposed to be good at STEM and girls (especially the cool girls, who were the ones who got dates and I desperately wanted to be included in) were good at Literature. So guess what? I got good at literature. And went on to do Social Sciences. And it was boring and I was fascinated by theoretical physics and molecular biology but by that time I'd missed out on the math I needed to study these subjects at a high level.
I think the world has changed now. But I'd love for this little girl to keep her options open as long as she can :)