Neat. Thankyou.

However, despite my initial misgivings of using a Math::* module with an overload interface -- mostly based on my bad experiences with using Math::BigInt way back when -- I was pleasantly surprised to discover that modifying the routine where the problem occurred from:

sub Q2b36 {
    my $n = shift;
...
[download]

to:

sub Q2b36 {
    my $n = uint64( shift );
...
[download]

Fixed all the problems with no other changes required. About as simple as a work around for Perl's deficiencies could get.

Once again. Thank you for Math::Int64 & Math::Int128.