C575
      +---------
72E38 | A4A670E9
       -EC3A8
        =====
        71A250
       -71BE6E
        ======
          93E9E
         -72E38
          =====
          7138C9
         -71BE6E
          ======
            CE72

base: 15
letters: 0123456789ABCDE
difficulty: hard
missing: D