While math intelligence predicts early math learning, by grades 5 through 10 confidence and study matter more.
It's not how smart students are but how motivated they are and how they study that determines their growth in math achievement.
"While intelligence as assessed by IQ tests is important in the early stages of developing mathematical competence, motivation and study skills play a more important role in students' subsequent growth,"...
Intelligence was strongly linked to students' math achievement, but only in the initial development of competence in the subject. Motivation and study skills turned out to be more important factors in terms of students' growth (their learning curve or ability to learn) in math. Students who felt competent; were intrinsically motivated; used skills like summarizing, explaining, and making connections to other materials; and avoided rote learning showed more growth in math achievement than those who didn't. In contrast, students' intelligence had no relation to growth in math achievement.