$2 \times \_3P\_1 \times \_2C\_2=6$. 
How many different four-digit numbers can be formed by rearranging the four digits in $2004$?~(2004 AMC 8 Problem, Question \#2) 

  - $$4$$ 
  - $$6$$ 
  - $$16$$ 
  - $$24$$ 
  - $$81$$ 