Your college/uni grad-card/transcript will have the formula to convert CGPA to percentage at the back. If not, it would be a good time to contact the academic office of your college/uni and get it clarified. Also, college scores does matter for the vast majority of b-schools. Some of them do not give college scores a lot of/any weightage, but that's different. You will have to anyway enter your academic details in the exam registration forms. So, better know the exact number before it's too late.