Question 1076713
Let's write
 &###&&

Like this:
  CnnnDE

C is one of { "W", "X", "Y", "Z" }    (—> 4 choices)
D is one of { ??? }  —>  the problem statement is a bit unclear on what D can be: can D be any letter A..Z or is D subject to some restriction like C and E?   I will assume D can be A..Z, so 26 choices.
E is one of { "A", "B" }                 (—> 2 choices)

n is 0..9 inclusive   —>  10 choices

Since repetition is allowed, just multiply the number of choices for each position and you'll have your answer.   Assuming the 2nd letter (D) can be any alphabet character (26 choices) you get:
—

       ans =  {{{ 4*10*10*10*26*2 }}}
—
If D has restrictions, adjust your calculation accordingly.