Question

You need to have a password with 55 letters followed by 33 odd digits between 00 and 99, inclusive. if the characters and digits cannot be used more than once, how many choices do you have for your password?

Answer 1

Mahtematical and statistical reasoning makes it evident that there is a mistake in the writing of the question and the digits were duplicated. So the right question is:

"You need to have a password with 5 letters followed by 3 odd digits between 0 and 9, inclusive. If the characters and digits cannot be used more than once, how many choices do you have for your passwor?"

The solution is:

5 letters from 26 with no repetition => 26*25*24*23*22 different choices.

odd digits are 1, 3, 5, 7 and 9 => 5 different digits to choose

3 digits from 5 with no repetition => 5*4*3 = 60

Then, the total number of choices is: 26*25*24*23*22*60 = 473,616,000

Answer: 473,616,000 choices.