#!/usr/bin/perl -w
use strict;

my @test = qw (20o3oo something 02oo-s 2o0o0o-s 2OoOO);

foreach my $x (@test)
{
  print "$x becomes ";
  
  $x =~ s|(\d[\doO]+)|my $a = $1;  $a=~tr/oO/00/; $a|e; 
  
  print "$x\n";
}
__END__
20o3oo becomes 200300
something becomes something
02oo-s becomes 0200-s
2o0o0o-s becomes 200000-s
2OoOO becomes 20000