#!/user/bin/perl

use strict;
use warnings;

print "Welcome to the mathq program\n";

while (1) {
    print "Enter a number\n";
    chomp(my $n = <STDIN>);
    die "Goodbye\n" if $n eq 'q';
    chomp(my $m = <STDIN>);
    print "$n + $m = ", $n+$m, "\n",
          "$n - $m = ", $n-$m, "\n",
          "$n x $m = ", $n*$m, "\n",
      $m == 0 ? '' :
         ("$n / $m = ", $n/$m), "\n";
}

__END__

##</code><code>##

#!/user/bin/perl

use strict;
use warnings;

print "Welcome to the mathq program\n";

INPUT: while (1) {
    print "Enter a number\n";
    chomp(my $n = <STDIN>);
    die "Goodbye\n" if $n eq 'q';
    chomp(my $m = <STDIN>);
    for ($n,$m) {
        warn "Invalid input: Type a number or 'q' to quit\n" and
          next INPUT unless /\A\d+\z/;
        # use your own more refined validation there
    }
    print "$n + $m = ", $n+$m, "\n",
          "$n - $m = ", $n-$m, "\n",
          "$n x $m = ", $n*$m, "\n",
      $m == 0 ? '' :
         ("$n / $m = ", $n/$m), "\n";
}

__END__

##</code><code>##

    ($n,$m) = map {
        ;no warnings 'numeric';
        $_+0;
    } $n, $m;