What about using Scalar::Util.

use Scalar::Util qw/looks_like_number/;
my @data = ( -123.004, -.008, 0, -0, .0987, 1.0, 12345, 'd', 'test' );

foreach my $value (@data) {
  print( looks_like_number($value) ? "true\n" : "false\n" );
}
__OUTPUT__
true
true
true
true
true
true
true
false
false
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