#!/usr/bin/perl
use strict;
use warnings;

use Tk;

my @numbers = ( -1.22, 47.11, 42, 13.5, 10000.2, -213);

for (@numbers) {
    $_ = sprintf "%9.2f", $_;
}

my $mw = new MainWindow;

my $lb = $mw->Listbox(-font => '{Courier New} 12 {normal}')->pack();


$lb->insert('end', "$_") for (@numbers);

MainLoop();