A valid password on a Web site contains 3 letters (A-Z, 26 total), followed by 3 digits (0-9). Letters and numbers can be repeated. The number of possible passwords equals _____.

A. 26*25*24+10*9*8

B. 26^3+10^3

C. 26^3*10^3

D.26*25*24*10*9*8

Each of the first three characters is 26 choices each (repetition permitted).

Each of the following digits has 10 choices (numbers can be repeated).

Total number of distinct passwords is the product of all these number of choices.

To find the number of possible passwords that can be created using 3 letters followed by 3 digits, we need to calculate the total number of choices for each position and then multiply them.

First, let's consider the options for the letters. There are 26 letters in the English alphabet, and since repetition is allowed, we have 26 choices for each letter position. So, the number of choices for the letter positions is 26 * 26 * 26 = 26^3.

Next, let's consider the options for the digits. There are 10 digits from 0 to 9, and again, repetition is allowed. So, the number of choices for the digit positions is 10 * 10 * 10 = 10^3.

To find the total number of possible passwords, we multiply the number of choices for the letter positions by the number of choices for the digit positions: 26^3 * 10^3.

Thus, the correct answer is C. 26^3 * 10^3.