#!/usr/bin/perl

use warnings;
use strict;

for (my $i = 0 ; $i < 9 ; $i += 0.1){
   print "$i\n";
}

OUTPUT (truncated):
(...)
4.9
5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.99999999999999
6.09999999999999
6.19999999999999
6.29999999999999
6.39999999999999
6.49999999999999
(...)