PYPU
      +---------
JJPYN | RJYPRUPJ
       -JJPYN
        =====
        NUNYJU
       -PQRQJP
        ======
          JYQQP
         -JJPYN
          =====
           PRPQJ

base: 7
letters: JNPQRUY
difficulty: intermediate
restrictions: no multiplication