?????????
      +----------
58757 | 37453A11A
       -A8BAB
        =====
        58165A
       -547061
        ======
         599A01
        -507416
         ======
           A62B1
          -08606
           =====
           5691BA
          -537AB9
           ======
           ??????

base: 12
letters: 0123456789AB
difficulty: intermediate