Mainly used in physics, all theories in physics need to use mathematics, especially aerospace majors, which are more dependent on mathematics. And economics, almost all need mathematical modeling. There is also architecture, which requires higher linear algebra. But mathematics is a basic subject, and its direct application is not great. You'd better choose a part-time job, but you can major in it. Mathematics is not for you to use, otherwise junior high school will be enough. Learning mathematics is to cultivate your mathematical thinking. Now many big companies pay attention to this. To some extent, mathematics is a hot major.