????????
      +---------
4747B | 6A791A85
       -4747B
        =====
        14AABA
       -1030A1
        ======
         A3B498
        - 4747B
         ======
          4A3A45
         -436A31
          ======
          ??????

base: 12
letters: 0123456789AB
difficulty: intermediate
hints: 1 << 2
missing: 2