Hi there,

Yes you can pursue bsc maths even if you belong from commerce stream. Only condition is that you should have studied maths till 12th standard.  Some of colleges insist for science stream in 12th standard for admission in bsc maths but most of colleges offers admission to students who belongs from commerce stream in bsc mathematics course.

Eligibility criteris for admission in bsc course differs from one institute to other.

Most of colleges conduct entrance exam or accept results of various entrance exam.

For more details  follow this link: https://www.google.com/amp/s/www.careers360.com/courses/bsc-in-mathematics/amp

Hope it helps you.

Good luck!