sir , what is the scope of mathematics and computing in IIT’s or ISM. ? is it better than mining eng. at ISM ?

From what all I've heard M&C is a good choice especially for people who are very enthusiastic about computer science but miss out on CS due to their AIRs.
It's not a dull branch. Many of their courses are same as that of CS Dept.
The job opportunities are also decent for the branch. Most of the companies that open for CS are open for M&C too.