There is no requirement for percentage.if you want to give NDA exam then you must have to pass 12th exam. marks and stream are do not matter.
he minimum qualification is 12th pass and the percentage does not count towards your selection. All that matters is the marks you score in NDA entrance examination based on which you be called up for SSB Interview wherein your leadership, OLQ and personality will be assessed. Only if you qualify in SSB you will be called for Medical . After Medical fitness you will be called up to training.