$4\times4\times3=48$ 
Martin uses the five digits $$0$$, $$1$$, $$3$$, $$7$$, $$9$$ to make some numbers (each digit can only be used once).  How many different three-digit numbers can be made? 
  - $$60$$ 
  - $$50$$ 
  - $$48$$ 
  - $$40$$ 