Much simpler: 
use bigint; 
my $n = 123456789123456; 
print $n->as_hex;

[download]
or just 
use bigint;
print 123456789123456->as_hex

[download]
"What should it profit a man, if he should win a flame war, yet lose his cool?"

In reply to Re^3: long integer to hexadecimal conversion by Joost
in thread long integer to hexadecimal conversion by perl_fan

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