GRPAW
       +-----------
UPXRYA | ATGFAUFRXU
        -UPXRYA
         ======
         UFXAXYF
        -UGWYPUY
         =======
          URXGWPR
         -UFGARXU
          =======
           WRUTPFX
          -WAUYXYP
           =======
             PRRRGU
            -ARGAUT
             ======
             WXAXAP

base: 10
letters: AFGPRTUWXY
difficulty: intermediate
restrictions: no multiplication