NDA examination is conducted by UPSC twice every year for the young boys to join the Indian defence forces as an officer

The best book for NDA preparation is Pathfinder for NDA & NA Entrance Examination which serves as National Defence Academy and Naval Academy.

NDA Eligibility:

for Army : 12th Class pass of the 10+2 pattern of School Education or equivalent examination conducted by a State Education Board or a University.

for Air Force, Navy and Naval Academy : 12th Class pass of the 10+2 pattern of School Education or equivalent examination conducted by a State Education Board or a University with Physics and Mathematics subjects

Physical Standards:

There should be no evidence of weak constitution, obesity or any bodily defects. The weight vs height ratio should be there.

The minimum height required is 157 cm. Though in case of air force, this requirement is 162.5cm.

Mathematics includes the following topics:

Mathematical section

Sets and relations along with functions,
binary and complex numbers
series and sequences
quadratic equations
binomial theorem
matrix and determinants
logarithms
trigonometry
topics in geometry like triangles
coordinates
circles
cones
3D geometry
The aspects of functions
limits
differentiation
derivatives
integration
vector algebra
probability theory
statistics
and area under curves