Hii Biswaprakash!
If you go for MSc mathematics or even Integrated course from any of the IITs, the placements are good. Although, most of the students choose to go for higher studies and research, because the government provided such good facilities and pays for such brilliant minds. But, those who sit for placements, get placed into leading companies.
Hope this helps.
Good luck!

Hello Aspirant

As you have not mentioned any IIT,have giving you a generalized update with regards to IIT Kanpur

The average salary is around 8-11 Lakhs.

Recruiting Companies are as follows

1. Acc Limited
2. Accenture
3. Ashok Leyland
4. Citigroup
5. DD News
6. Deutsche Bank
7. Qualcomm
8. Urban clap
9. Yahoo
10. ITC
11. Infosys
12. IBM
13. Google
14. Myntra
15. Nse

I hope this helps regards!