#!usr/bin/perl
use say;
use strict;
use warnings;
use Math::Roman qw(roman);
use Scalar::Util qw(looks_like_number);

my @array = ("8", "", 8, "132.8", 132.8, "III", roman('III'));
foreach my $array_element (@array) {
    if (looks_like_number($array_element)) {
	say "Element: ".$array_element." is a number";
    } else {
	say "Element ".$array_element." isn't a number";
    }
}

__END__

$ perl test.pl
Element: 8 is a number
Element  isn't a number
Element: 8 is a number
Element: 132.8 is a number
Element: 132.8 is a number
Element III isn't a number
Element: III is a number