2B43
      +---------
1331C | 0915532A
       -CC207
        =====
         EE253
        -EAC5B
         =====
          468D2
         -4AA45
          =====
           2C0AA
          -2412B
           =====
            3C48

base: 15
letters: 0123456789ABCDE
difficulty: hard