Hey!

The subject taken in class 10+2 has nothing to do with the Civil Services Examination. Your subjects in 12th does not have any effect on Civil Services exam. Even subject in bachelor's degree has nothing to do with Civil Services exam.

Also, Mathematics is not compulsory to appear for the Bank Clerk Exam. For Bank Clerk Exam you must have completed graduation from any recognized college or university in any stream. So Maths is not compulsory. But in competitive exam, you will have to answer questions asked from Mathematics also.

Hope this answer helps!