Hey,
If you are willing to go for Bachelor of Science in Computer Science then you must have studied 12th with Mathematics as one of the main subjects with a minimum 45 percent marks in aggregate from a recognised board.
B.Sc in Computer Science is a three year undergraduate programme that teaches you about coding,language,web applications etcetera.
It is basically a Science course.
Even if you go for Bachelor of Computer Applications you need to have studied Mathematics as one of the main subjects.However,some private colleges give admission in BCA to those without Maths.
In general,you must study Mathematics in order to pursue Computer Science.
Hope this helps.
Good luck.