Admissions will be according to the rules of Calcutta University that is through overall merit and entrance exams conducted by the university. 

For B.Sc. you will require a score of 85% or above to secure a seat for admission. It also depends on the subject you are applying for. 

To qualify in the first round of counselling you will require a minimum of 93% aggregate, but this percentage gradually drops down to 87–88% in the second counselling. 

It also depends on the basis they calculate the percentile, like for Economics, mathematics marks is considered. The cut off for microbiology and statistics are much higher when compared to other science subjects, so it varies.