#!/usr/bin/perl
use strict;
use warnings;
use Win32::GuiTest qw(SendKeys);
use Win32::KeyState qw(GetNumLock); # $self->toot('horn');
GetNumLock() or SendKeys("{NUMLOCK}");

my $number;
GET_NUM: {
  print "Please enter a number between 0 and 9 and press <Enter>.\n";
  $number = <STDIN>;
  chomp $number;
  redo if ($number !~ /^\d$/);
}
print "You entered $number.\n";