?????????
      +----------
D69C3 | 36208D1AB
       -37D31
        =====
         4822D1
        -AC0BD7
         ======
          A5785A
         -A8377B
          ======
            9274B
           -D69C3
            =====
           ??????

base: 14
letters: 0123456789ABCD
difficulty: intermediate