Question

Suppose that a password consists of 2 letters followed by 4 digits, where there are 26 letters and 10 digits to choose from. How many different passwords are possible?

Answer 1

68250

Explanation:

Number of ways in which 2 letters can be selected out of 26 letters = 26 c 2 = 26 ! / ( 2! x 24! ) = 325

Number of ways in which 4 digits can be selected out of 10 digits = 10 c 4 = 10 ! / ( 4! x 6! ) = 210

So , total number of ways in which password containing 2 letters & 4 digits can be made = 325 x 210 = 68250