AC76
      +---------
AC705 | E7D2C0A6
       -AC705
        =====
         1E820
        -9B503
         =====
          3C1DA
         -D5B64
          =====
          A251A6
         -AEEDE3
          ======
           A228A

base: 15
letters: 0123456789ABCDE
difficulty: medium