Firstly ISI don't offers the course of BSc Mathematics instead it offers the degree B.Math which means Bachelor of Mathematics. Also if you get into ISI and you have good academic records then you can directly take admission to M.Math program after your B.Math directly and without any entrance.

The B.Math examination for the session 2022 isn't released it. I would recommend you to keep an eye on the official website, in order to get notified.

To know more about the ISI visit the link below:

https://www.isical.ac.in/~admission/

To know more about the ISI visit the link below:

https://www.careers360.com/university/indian-statistical-institute-kolkata

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