Kenneth Rosen Edition 7 Exercise 6.3 Question 39 (Page No. 415)

Question

How many license plates consisting of three letters followed by three digits contain no letter or digit twice?

Answer 1

given;

         _    _    _         _    _    _    first three blanks can have 3 non repeating letters and next three could have 3 non repeating digits

here the first blank can be filled with 26 letters and second one could contain  only 25 ,similarly thirs one has 24.also 4^th blank shouls have digits that is from 0 to 9,i.e 10 digits can get filled in 4^th one,9 get filled in 5^th,8 get filled in 6^th.

i.e;    26x25x24   x   10x9x8 =11232000 ways.     

here