arbitrary numbers routine

i need an arbitrary numbers unit that provides the basics like:

procedure multiply(a,b:arbnum;var c:arbnum);
(*which returns c=a*b and a,b and c are all arbitrary numbers*)

procedure divide(a,b:arbnum;var c:arbnum);
(*which returns c=a/b and a,b and c are all arbitrary numbers*)

procedure add(a,b:arbnum;var c:arbnum);
(*which returns c=a+b and a,b and c are all arbitrary numbers*)

procedure subtract(a,b:arbnum;var a,b:arbnum);
(*which returns c=a-b and a,b and c are all arbitrary numbers*)

thanx in advance
--
  Eric
homepage: http://www.shsu.edu/~stdemm01
email: mailto:stdem...@shsu.edu
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