????????
      +---------
35479 | 23A22A54
       -35479
        =====
        00627A
       - 1A112
        ======
         534035
        -56A2A5
         ======
          51AA64
         -5A0A40
          ======
          ??????

base: 11
letters: 0123456789A
difficulty: intermediate
missing: 8