#!/usr/bin/perl

use strict;
use warnings;

my $c = 0;

while (1) {
    $c ++;
    my $r = rand;
    die "Failed ($r) after $c attempts.\n" if substr ($r, 2) =~ /\D/;
}
 
__END__
Failed (1.13079331747201195e-05) after 17507 attempts.