WTQ
      +---------
LGWFN | XHTFREER
       -NWGHQT
        ======
         XXLGQE
        -XNNUUH
         ======
          QQWLNR
         - LGWFN
          ======
           RNWUW

base: 13
letters: EFGHJLNQRTUWX
difficulty: hard
restrictions: no multiplication
missing: J