IGNOU BSc has 2 types of subjects - Theory and Practical. It’s further divided into - Assignments and Term end theory exams.
In order to calculate total marks in a paper out of 100 - Assignment marks* 0.3 + Theory marks*0.7. The calculated sum will be your overall marks out of 100.
To know the actual marks that will be on your marks sheet follow this rule:
For theory-
If it is a 4 credits course divide the marks by 2.
If it is a six-credit course, divide it by 4/3.
If it is a 2 credit course divide it by 4
This is because 8,6,4,2 credit courses have total marks out of 100, 75, 50 & 25 respectively.
For practical-
It has two parts - Lab 1 and Lab 2
Total marks out of 100 = Lab 1 mark*0.7 + Lab 2 marks*0.3. To calculate total marks follow the same rule mentioned above. Total credits in BSc-96
Therefore total marks will be 96/8=12 hundred.=1200
Net percentage will be = Total marks out of 1200 /Twelve hundred multiplied by 100 .
One of my friends studied at Calcutta University, so I might be able to give you some details about it.
Finally, you should keep in mind that other mentioned universities may not be as old and experienced as CU, but they will show a bit of leniency while giving marks. So ultimately the decision is yours, whether you want to study in a reputed university with a strong and reliable alumni network or opt for the easier way out by getting admission to newer institutions.