gmp, The GNU Multiple Precision Arithmetic Library
 
Free library for arbitrary precision arithmetic, operating on signed integers, rational numbers, and floating point numbers.

Website: http://www.gmplib.org
Platforms supported: Win32, Linux
Headers to include: gmp.bi
Header version: 4.1.4

Example

#include once "gmp.bi"

Dim As mpz_ptr bignum = Allocate(SizeOf(__mpz_struct))
mpz_init_set_si(bignum, 2)
mpz_pow_ui(bignum, bignum, 65536)

Print "2^65536 = ";
Dim As ZString Ptr s = mpz_get_str(0, 10, bignum)
Print *s;
Deallocate(s)
Print

mpz_clear(bignum)
Deallocate(bignum)