#!/bin/perl

use strict;
use warnings;

my %tab;
foreach (<DATA>) {
        chomp;
        $tab{$1}=$2  if /^\s*0(\d+)\s+(.*)/; # e.g. 30 -> Berlin
        # you can compute min/max of the prefix here (s. below)
}

                            # already normalised w/o leading 0
NUMBER: foreach my $num ( qw(204112345 3304123456 3145666 301234567) ) {  
            for (my $len=5; $len>=2; $len--) { 
                 # assumes max. prefix lenght is 5, min. is 2
                 my $prefix = substr($num,0,$len);
                 if (defined (my $town=$tab{$prefix})) {
                     printf "0%-12s = %5s-%-7s in sunny %s\n", 
                              $num,  "0$prefix", 
                              substr($num,$len), $town;
                     next NUMBER;
                 }
            }
            print "NO MATCH FOR: 0$num\n";
}

__DATA__
0201    Essen, Ruhr
0202    Wuppertal
0203    Duisburg
02041    Bottrop
02043    Gladbeck Westf
0208    Muelheim a.d. Ruhr
0208    Oberhausen Rheinl
212    Solingen
02129    Haan Rheinl
030    Berlin
03301    Oranienburg
03302    Hennigsdorf
03303    Birkenwerder
03304    Velten
033051    Nassenheide
033053    Zehlendorf Kr Oberhav
033054    Liebenwalde
033055    Kremmen
033056    Muehlenbeck Kr Oberhav
03306    Gransee
03307    Zehdenick