VC++ never uses more than 64 bits to represent numbers. You can delare a 64
bit integer like so
__int64 x;
x though, will have less than two dozen decimal digist.
You can declare floating point numbers like so:
double y;
64 bits will be used to contain y's value, around 53 or so will be used for
the "mantissa", the rest for a sign and an exponent. Doubles exist in a
wider range, but most numbers can not be expressed exactly.
Often when people need such large numbers as you want, the goal has to do
with cryptography. There are a number of libraries crypto available. You
should be able to google for them. This page may be helpful