Question

A license plate has to have 3 letters followed by 3 digits. How many license plates can be formed if :
1. the letters and nos. cannot be repeated 2. if the nos. and letters can be repeated. THANKS !!!!!

Answer 1

2.
when nos. and letters are repeated
=26*26*26*10*10*10=?
1.
when nos. and letters are not repeated
=26*25*24*10*9*8=?

Answer 2

is that right ? yes it seems to be right, I am trying to digest :)