NNXL
      +---------
NLYPP | NHPYMGGP
       -NLYPP
        =====
         EXMHG
        -NLYPP
         =====
         NYQYUG
        -NPWWXH
         ======
           HLUWP
          -QXYXW
           =====
            LRWL

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