Hello Aspirant

While calculating marks for any competitive exam, you need to take into consideration all the marks of the subjects that were your main papers in the 12th Board Examination. For Example, you had science in your 12th grade, meaning you had Physics, Chemistry, Math, English, and one other subject. You will calculate the marks of these subjects, unless stated otherwise.

In the CAT exam, after you've gotten your marks, your 12th marks don't really matter, they just need to see that you have an aggregate of 50% in the 12th Board Exams. It all comes down to your Group Discussions and Personal Interviews and to some extent, your performance in graduation and your work experience.

Hope this helps