for my $i (1..20) {
  print "$i: ";
  print (1-1/2000)**$i;
  print " - ";
  print (1-1/2000)**int($i);
  print " - ";
  print "" . (1-1/2000)**$i;
  print "\n";
}

##</code><code>##

1: 0.9995 - 0.9995 - 0.9995
2: 0.9995 - 0.9995 - 0.99900025
3: 0.9995 - 0.9995 - 0.998500749875
4: 0.9995 - 0.9995 - 0.998001499500063
5: 0.9995 - 0.9995 - 0.997502498750313
6: 0.9995 - 0.9995 - 0.997003747500938
7: 0.9995 - 0.9995 - 0.996505245627187
8: 0.9995 - 0.9995 - 0.996006993004374
9: 0.9995 - 0.9995 - 0.995508989507872
10: 0.9995 - 0.9995 - 0.995011235013118
11: 0.9995 - 0.9995 - 0.994513729395611
12: 0.9995 - 0.9995 - 0.994016472530913
13: 0.9995 - 0.9995 - 0.993519464294648
14: 0.9995 - 0.9995 - 0.993022704562501
15: 0.9995 - 0.9995 - 0.99252619321022
16: 0.9995 - 0.9995 - 0.992029930113615
17: 0.9995 - 0.9995 - 0.991533915148558
18: 0.9995 - 0.9995 - 0.991038148190984
19: 0.9995 - 0.9995 - 0.990542629116888
20: 0.9995 - 0.9995 - 0.99004735780233