my @list = ( 5, 11, 7);
my @timesthree = map { $_ *= 3 } (@list);

##</code><code>##

my @timesthree_onlyfives = map { $_ *= 3 if ($_ % 5 == 0) } (@list);

##</code><code>##

my @all_timesthree_onlyfives = 
   map { 
      if ($_ % 5 ==0) {
         $_ *= 5;
      } else {
         return $_;
      }
   } (@list);