RQFN
      +---------
LUTEU | JHQQHFWX
       -XUNJE
        =====
         FNWXF
        -LUTEU
         =====
         WNXJXW
        -WNXWLM
         ======
            HLEX

base: 13
letters: EFHJLMNQRTUWX
difficulty: intermediate
restrictions: no multiplication