How do languages such as Python overcome C's Integral data limits?

Question

While doing some random experimentation with a factorial program in C, Python and Scheme. I came across this fact:

In C, using 'unsigned long long' data type, the largest factorial I can print is of 65. which is '9223372036854775808' that is 19 digits as specified here.

In Python, I can find the factorial of a number as large as 999 which consists of a large number of digits, much more than 19.

How does CPython achieve this? Does it use a data type like 'octaword' ?

I might be missing some fundamental facts here. So, I would appreciate some insights and/or references to read. Thanks!

UPDATE: Thank you all for the explanation. Does that means, CPython is using the GNU Multi-precision library (or some other similar library)?

UPDATE 2: I am looking for Python's 'bignum' implementation in the sources. Where exactly it is? Its here at http://svn.python.org/view/python/trunk/Objects/longobject.c?view=markup. Thanks Baishampayan.

Answer 1

It's called Arbitrary Precision Arithmetic. There's more here: http://en.wikipedia.org/wiki/Arbitrary-precision_arithmetic