johngg@abouriou ~/perl/Monks $ perl -Mstrict -Mwarnings -E '
say for
   map {
       my $w = $_;
       map {
           my $x = $_;
           map {
               my $y = $_;
               map {
                   my $z = $_;
                   join q{}, $w, $x, $y, $z;
               } ( $y + 1 ) .. 9
           } ( $x + 1 ) .. 8
       } ( $w + 1 ) .. 7
   } 0 .. 6;' | wc -l
210