Hi Shivansh,

Yes, you can take commerce with math in class 11. You just have to fulfill the basic eligibility criteria to opt for commerce with math in class 11.
Most schools in India allow their students to take this combination because it is one of the most popular stream , especially for those students who want to pursue professional courses like CA, CFA, B.Com (Hons), B.A. Economics (Hons), etc.
You will study the following core subjects if you opt for commerce with math in Class 11th:

Accountancy.
Economics.
Business Studies.
Mathematics.
English.

All the best.

Thank you.
Regards,

(//B.Com)