6EE6
      +---------
1A6A1 | 86396B2B
       -1A6A1
        =====
        ABACDB
       -A7578E
        ======
         A7E512
        -A7578E
         ======
           14D3B
          -1A6A1
           =====
            C76E

base: 15
letters: 0123456789ABCDE
difficulty: challenging
missing: 0