????????
      +---------
B8373 | 5990BD86
       -D2C68
        =====
        B9387D
       -BD5640
        ======
         B8B158
        -B69215
         ======
           AB5D6
          -36501
           =====
           ?????

base: 14
letters: 0123456789ABCD
difficulty: medium