YYE
      +---------
FEMXR | XEREEXXH
       -XTEYYR
        ======
         HXTTXX
        -XTEYYR
         ======
          FQXMXH
         -FYMHER
          ======
           HYFHH

base: 9
letters: EFHMQRTXY
difficulty: medium
restrictions: no multiplication