?????????
      +----------
3DFB7 | 1BBACE5C4
       -3DFB7
        =====
        33BEDE
       -33282E
        ======
          71265
         -AA4BF
          =====
           0A98C
          -E4C80
           =====
            7CF44
           -7C43A
            =====
            ?????

base: 16
letters: 0123456789ABCDEF
difficulty: medium