Thanks - ..at a command line when I enter the following:
>perl -Mbignum=a,50 -le 'print 0xbe91cfb586466d02'...it returns: 13731985117378145538 (exactly the value I want).
The Perl script I'm running has at the top the following line: #!/fs/COTS/gnu/bin/AIX/perl - followed by the rest of the source code. I'm now wondering how I can introduce the "-Mbignum" statement into the source code in order to get the precision I'm looking for - any ideas? ..thanks