Oops the formatting got fucked up. What I meant was:

  r => rx
  123 => 123x

and:

  / => i 
  // => ii 
  /// => iii 
  ///////// => ix

  3 => xxx 
  7 => xxxxxxx 
  9 => xxxxxxxxx 
  11 => xxxxxxxxxxx

  iii => 3 
  xii => 12 
  xvi => 16