pointers question for an interview

Hi everybody,

I'm trying to figure out a piece of programm for an interview.
I would appriciate any help!!

#pragma pack(push)
#pragma pack(1)xd
struct P
{
char c[100];
short s[4];
unsigned short us[8];
};
#pragma pack(pop)
struct P* Ptr = (struct P *) 1000; // what is this line refers to?
Ptr += 3;

what does Ptr points to?

Thanks!!
MichalB