????????
      +---------
32A86 | 910EE521
       -32A86
        =====
        C40AC5
       - 32A86
        ======
         0DAD72
        -09712E
         ======
          6E8881
         -C51DDB
          ======
          ??????

base: 15
letters: 0123456789ABCDE
difficulty: hard