If you choose, of course, the first thing is to be a teacher. But only if you like being a teacher. If you are not very dominant in mathematics and you have other talents, of course, choosing what you have is your best choice. If you are interested in computers, you also have a foundation in this field. Of course, people who have studied mathematics are a good choice. Then you can change your major through postgraduate entrance examination and find your favorite career for the future. That's also a good choice. In a word, learning math is a good choice.

There is probably a direction for employment. In computer, such as numerical calculation, software development, testing, data analysis, etc. , financial data analysis and financial software development and testing. Choose a good course according to your future work will. So you should plan your career well when you are studying, and don't wait until graduation, which will waste time and miss many opportunities.

I hope I can help you.