$ perl5.00503 -le 'print $]'
5.00503
$ perl5.6.0 -le 'print $]'
5.006
$ perl5.6.1 -le 'print $]'
5.006001

##</code><code>##

$ perl5.00503 -le 'printf "v%d.%d.%d\n", $] =~ /^(\d+)\.(\d{3})(\d*)/'
v5.5.3
$ perl5.6.0 -le 'printf "v%d.%d.%d\n", $] =~ /^(\d+)\.(\d{3})(\d*)/'
v5.6.0
$ perl5.6.1 -le 'printf "v%d.%d.%d\n", $] =~ /^(\d+)\.(\d{3})(\d*)/'
v5.6.1