Question

You need to select a 5-character password for an account. You may use the digits 0-9 or the lower case letters a-z. You may repeat digits or letters. How many possible passwords are there?

Answer 1

`36^5`

Explanation:

Since the digits are ten, and the letters are twenty-six, we have thirty-six possible character in total.

You can repeat characters, so every place is independent on the content of the others. This means that you have `36` choices for the character in the first place, `36` for the second, and so on. This means `36*36*36*36*36` in total, which is `36^5`.