CGCX
      +---------
FWWNU | HWHCWUEE
       -FWWNU
        =====
        MWUQUU
       -MWWCQU
        ======
          UXXWE
         -FWWNU
          =====
          NXHQRE
         -NXWCXW
          ======
            HXGE

base: 12
letters: CEFGHMNQRUWX
difficulty: medium
restrictions: no multiplication