As you said, you are a maths student, it is always welcome to pursue whatever UG you can. It is good to choose management studies. After aspiring what you want to achieve in UPSC with managerial skills. It is also known that MBA is in boom and easily to get recruited and gives you confidence to stand for UPSC many times.

dear aspirant,

You can definetelyy do if you can manage your time accordingly and create a balance between prepation and academy but it would be more useful if you choose social wing that includes history, political science , sociology or economics which will be be useful for your academy as well as for your upsc preparation.