There are basically 2 papers in NDA examination.

Mathematics - 300 marks - 120 questions

General aptitude test - 600 marks - 150 ques.

Negative marking - 1/3 for both papers.

Criteria for selection

You need to score min 30 % in each paper .

Securing above 120 marks in Maths and 150-160 marks in GAT assures clearing of both papers individually.

Since cutoff varies from year to its hard to predict final cutoff but a total score of 350 and above can assure call for SSB.

I hope this helps.

Regards

Madhur