#!/usr/bin/perl -l --
use strict;
use warnings;

my @s =qw(nan naNo inf InfInity infimum foo bar 123dd);
print "$_ => ", $_+0 for @s;

__END__

Argument "naNo" isn't numeric in addition (+) at a.pl line 7.
Argument "infimum" isn't numeric in addition (+) at a.pl line 7.
Argument "foo" isn't numeric in addition (+) at a.pl line 7.
Argument "bar" isn't numeric in addition (+) at a.pl line 7.
Argument "123dd" isn't numeric in addition (+) at a.pl line 7.
nan => nan
naNo => nan
inf => inf
InfInity => inf
infimum => inf
foo => 0
bar => 0
123dd => 123