Primeform is the best "pocket calculator" for big numbers.

As a side effect it even tests for probable or proven primality too! :-)

It has many functions such as gcd, about the only useful thing that it

doesn't have is a modulo exponentiation :-( well it has it inside but you

can't use it from the UI )-:

I have recently found a new toy -

GNU Multiple Precision Arithmetic Library (GMP)

http://swox.com/gmp/
and I've heard good things about LiDIA which uses GMP,

linked amongst others from that web page.

Cheers,

Paul Landon

Barubary wrote:

> Can someone direct me to a program that'll let me

> add/subtract/multiply/divide 20000 bit numbers?

>

> Thanks,

>

> -- Barubary