Operation with long_numbers

[draqula]

OK, I couldn't find anything about this topic, so it's either that i'm not looking where I should, or i'm not looking for what i should. If there is such a topic on this forum, then the search tool sux .

Long doesn't stand for the numeric type LONG <aka 0-2^16-1>, but really long <aka many digits> numbers, which wouldn't fit in any numeric type. So these numbers are stored as arrays (1 dim: e.g. 1024 is stored in num: num[1]=1, num[2]=0, num[3]=2, num[4]=4).

My question is: does anyone have any idea about mathematical algorithms to use with such numbers?? (where to find info about that, or even already made)

Addition is easy: just add array elements and watch out for carry...
What about multiplication, or even more complex operations??

PS: yep, search tool not that reliable... found something on the 9th page of results...