use Number::Format;
my $x = new Number::Format(-thousands_sep => ' ');
my $number = 1234567890;
print $x->format_number($number);

##</code><code>##

$ perl example.pl
1 234 567 890

##</code><code>##

my $number = 1234567890;
print format_number($number);

sub format_number{
	my($x) = @_;
	$x = reverse $x;
	$x =~ s/(\d{3})/$1 /g;
	$x = reverse $x;
	return $x;
}

##</code><code>##

1 234 567 890