No DN College, Hisar dont offer a course in Bsc Hons Mathematics. As per the official website the courses offered in BSc are:

• Medical
• Biotechnology
• Computer science
• Electronics

Although the college have MSc program in Mathematics.

To know more you may visit official website stated below:

https://www.dncollege.com/#

To know more about the BSc Mathematics colleges in India you may visit the link below:

https://university.careers360.com/colleges/list-of-bsc-in-mathematics-degree-colleges-in-india

Now as you are interested in Mathematics I would say that for Mathematics the best colleges are ISI Bangalore, Kolkata, IISc. You should atleast attempt the entrance of ISI which if for the course of BMath. The curriculum is great and you will really get interested in the course if you are interested in Mathematics mostly Pure Mathematics.

To know more about ISI entrance visit the link below:

https://www.google.com/amp/s/www.careers360.com/exams/isi-admission-test/amp

I hope my answer helps. All the very best for your future endeavors!