JJXF
      +---------
XEJTN | YHYFWEEU
       -FHLYT
        =====
        HREYJE
       - FHLYT
        ======
         JTENHE
        -JHUYXJ
         ======
          LQNUXU
         -LUHHNE
          ======
           HJWJJ

base: 13
letters: EFHJLNQRTUWXY
difficulty: medium
restrictions: no multiplication