Hi!
One of the C++ programmers problems is to save integers more than '2^64-1'(we can save 0 to 2^64-1 in unsigned long long int).
It is the best bignum I ever have seen: Link.
It has operation: + , - , / , * , % , ^(pow) , gcd , lcp , abs.
Can work with ostream(cout), istream(cin).
Can convert to long long, string.
The best ability of this is fast multiplication.



