Question 938998
 password is 5 digits long
 first digit can filled with any of 10 digits ( 0-9 = 10 digits)
  second digit can be filled with remaining 9 digits ( as already 1 digit is being used)
   third digit can be filled with remaining 8 digits ( as already 2 digits  are being used)
   fourth digit can be filled with remaining 7 digits ( as already 3 digits are being used)
  fifth  digit can be filled with remaining 6 digits ( as already 4 digits are being used)
the maximum number of different passwords brad can have  =  10x9x8x7x6
                                                           =30240