How to fulfill the gap of mathematics to get admission for MCA? I have done B.Com and class 12th (without mathematics).

Harshal, even the students who have done Statistics or Business Maths or Business Statistics or QTas one of the subject at Graduation or 10+2 level) are eligible for admission to MCA. So, being a B.Com student you must have one of them. There are many institutions that offer admission in MCA without

MCA required math's compulsory in 10+2

You can check if any of the University offers this PG without Maths. You can also try to find out if any University offers MCM. It actually doesn't require maths.