An automobile number plate contains two letters followed by three digits, with the first digit not zero. If repetition is allowed, how many different number plates can be formed?

Each of the two letters has 26 choices. The first digit has 9 choices because it cannot be 0, and each of the last two digits has 10 choices. So the total number is $26\times 26\times 9\times 10\times 10=608400$. Option B would incorrectly allow 10 choices for the first digit.