ULR
       +---------
NENPPG | TEUFRGXR
        -NENPPG
         ======
         PTNGTFX
        -PXULPNR
         =======
          UPTNNGR
         -UFTFGLR
          =======
           PFEXTF

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