Question

I want to choose a license plate which is 3 characters long, where the first character is a letter, the last character is a digit, and the middle is either a letter or a digit. I also want there to be two characters on my license plate which are the same. How many ways are there for me to choose a license plate with these restrictions

Answer 1

Explanation:

* * *

let the middle digit is a letter.

as first and second letters are same so consider them as one letter.

It can be filled in 26 ways.

third place is filled in 10 ways (0,1,2,3,4,5,6,7,8,9)

total number of ways=26×10=260 ways

again consider second place is a digit.

so consider second and third place as one digit.

it can be filled in ways=10

first place can be filled in ways=26

Hence number of ways=26×10=260

so total number of ways=260+260=520