?????????
      +----------
29B57 | 38A9626B6
       -29B57
        =====
         612B2
        -A7B26
         =====
          99276
         -5B802
          =====
          2888AB
         -216945
          ======
           256886
          -2677AA
           ======
           ??????

base: 12
letters: 0123456789AB
difficulty: intermediate