I've searched through these boards and many others but only got some vague answers, so here's my request for help.

I'm doing alot of multiplication within a for loop and I was hoping I might be able to speed it up a bit. At the moment the multiplication is averaging approx 64 times a digitsum of greater than 1000.

At the moment I'm using a long interger class that stores all the digits in a char array but realise this may not be the best method. As well, a friend suggested I use a bit shifting method.

I've also looked into the GNU Multiple Precision Arithmetic Library which seems good and all, but all I want is the basic functions to be optimized, I don't think I need nor do I want that whole library. I have an unexplicable desire to code it mostly by myself =)

Any ideas on how to optimize multiplication (as well as division and modulus if time permits) would be extremely appreciated.