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

my @data = (
  '36000.0000',
  '12725.0000',
  '80000',
  '8123.2412'
);

sub fix_number {
  my $number = shift;
  $number = reverse sprintf("%.2f", $number);
  $number =~ s/(\d\d\d)(?=\d)(?!\d*\.)/$1,/g;
  $number =~ tr/.,/,./;
  return scalar reverse $number;
}

foreach (@data) {
  print fix_number($_), "\n";
}

exit;