#! perl
use Modern::Perl;

while (<DATA>)
{
    chomp;

    if (/ ^ (?: (?: -? \d+) | (?: -? \d+ \. \d+)) $ /x)
    {
        say 'Yes, ', $_, ' is a number';
    }
    else
    {
        say 'No, ',  $_, ' is not a number';
    }
}

__DATA__
4
-7
0.656
-67.35555
5.
56F
.32 
-.04