????????
      +---------
D2AD7 | 3F685A21
       -D2AD7
        =====
        1492BA
       - D2AD7
        ======
         721942
        -7125B3
         ======
          88D461
         -EFFECA
          ======
          ??????

base: 16
letters: 0123456789ABCDEF
difficulty: medium
missing: 0