There are 26 letters(from A to Z) and 10 numbers(ranging from 0 to 9).  A 3-string password is formed in the way: letter number number .Answer Q4-5.Q4How many different passwords that can be formed if the numbers CAN be used repeatedly?*1 分您的回答 這是必填問題Q5How many different passwords that can be formed if the numbers CANNOT be used repeatedly?

Suppose a company needs temporary passwords for the trial of a new payroll software. Each password will have one digit followed by three letters. The letter G and the digits 2, 3, 4, and 5 will not be used. So, there are 25 letters and 6 digits that will be used. Assume that the letters can be repeated. How many passwords can be created using this format?passwords

(b) To log on to a certain computer account, the user must type in a 5-letter password. In such a password, no letter may be repeated, and only the lower case of a letter may be used. How many such 5-letter passwords are possible? (There are 26 letters in the alphabet.)

a password consists of 3 letters from a to f inclusive and 4 digits from 0 to 9 inclusive.each letter and digit can only be usd once.how many different password can be formed?

A password must start with a letter, be at least 6 characters long, include a number, not include any whitespace, and include a special symbol. How many of the following passwords are valid?hello, goodbye, Maker1, dog!three, Oops_again, 1augh#3

Suppose a company needs temporary passwords for the trial of a new time management software. Each password will have one digit, followed by one letter, followed by two digits. The digit 7 will not be used. So, there are 26 letters and 9 digits that will be used. Assume that the digits can be repeated. How many passwords can be created using this format?