For some particular website, the password must start with the letter X. Then there must be 4 more charters, and each of those characters may be a numeric digit or a letter of the alphabet. How many different passwords are possible?

Answer

1,679,616

Q: How many choices do we have for the first character? A:We have only 1 choice for the first character, which must be the letter X.
Q: How many choices do we have for each of the remaining 4 characters? A:We have 36 choices for each of the remaining 4 characters (26 letters + 10 numbers).
Q: How many different passwords are possible? A:To find out, we multiply the number of choices together: 1 * 36 * 36 * 36 * 36 = 1,679,616.