21. At the Airtight Security Company, every employee must wear a badge with an identification code consisting of 2 letters of the 26 letters A-Z followed by 2 of the digits 0—9. Letters and digits may be repeated, but the first letter CANNOT be the letter O. How many different codes can be made?

Answer and Explanation

Your Answer is

Correct Answer is C

Explanation

Because letters and numbers can be repeated, the first position cannot be the letter O, so there are 25 possibilities for the first position, 26 possibilities for the second position, 10 possibilities for the third position, and 10 possibilities for the fourth position. There are also 10 possibilities for the position, so choose C