The percentile score cannot be calculated just by knowing an individual's marks only... it requires a really tough and complicated procedure which is performed by the conducting body to provide results.. Percentile score is based upon the relative grading of the candidates in a session so it differs from session to session that what Percentile score they will get in  particular marks. So if you have scored 128 marks then too knowing your marks won't tell you what Percentile score you have got.. Therefore it's better to visit NTA's official site and get your result from there which clearly mentions your Percentile score for the exam..
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