????????
      +---------
A3E5A | 92C85616
       -A3E5A
        =====
        0A8686
       -001917
        ======
          132C1
         -28515
          =====
          DDDB06
         - 670BF
          ======
          ??????

base: 16
letters: 0123456789ABCDEF
difficulty: medium
missing: 4