Most of the above are professional courses for sophomores, and the subject arrangement is different according to different schools and directions. For example, partial computers can learn algorithms, discrete mathematics, data structures, partial economics, and also learn macro and micro economics of western economics. How can I put it? Many people in this major are engaged in computers, if they are undergraduates. If you want to continue your studies, you can rely on statistics or big data (especially big data has high requirements for computers). Finance is also a good choice. Undergraduate education is really limited. Of course you want to be a teacher or something. It takes courage and talent to engage in pure mathematical theory.
You can only use your hands. If you don't understand, ask again. Please accept it if you are satisfied.