????????
      +---------
930A1 | 75B19802
       -58386
        =====
        478898
       -455B26
        ======
         9A6080
        -9991A1
         ======
          435552
         -4BA771
          ======
          ??????

base: 12
letters: 0123456789AB
difficulty: medium
otient: 9187