Hello Shiva, 

Percentage is not calculated in MAT instead the score is calculated in percentiles. To get good percentile, you must attempt the questions with accuracy of 7 correct for every 10 questions. The duration of the exam is 2 hours 30 mins and there are 200 objective question. This means you need to solve each question in 0.75mins. For every correct answer, you are awarded 1 mark and for every wrong answer 0.25 marks are deducted. This implies that 1 mark would be deducted, if four questions are wrong. The score is a composite score and hence is calculated from 800. You need to score above 600 to get approximately 95-99 percentile, referring this you can attempt 150-170 questions to score around 500 marks. 200 questions are divided into five sections namely, Critical Reasoning, Data Analysis and Sufficiency, Language Comprehension, Indian and Global Environment and Mathematical Skills. You need to start with the section that you are most acquainted with, so that solving those questions will take less time. In this way, you can spend more time on weaker sections or sections that you are not much familiar with.

Hope the information is useful to you.

All the best..!!!