Question

Customer account "numbers" for a certain company consist of 2 letters followed by 4 numbers.

Step 1 of 2 :  

How many different account numbers are possible if repetitions of letters and digits are allowed?

Answer 1

Here, the account number consists of 2 letters followed by 4 numbers.

For example, one of the account numbers can be

AB4567.

Now, repetitions are allowed.

Now, we have to answer how many different account numbers are possible if repetitions of letters and digits are allowed.

Therefore, the first two letters can be selected in 26 ways each as we have 26 letters in the alphabet.

Further, each of the 4 numbers can be selected in 10 ways as we have 10 digits from 0,1,...,9.

So, finally, we have

(26)*(26)*(10)*(10)*(10)*(10)

Hence, if repetitions of letters and digits are allowed then 6760000 different account numbers are possible.

This answers your question.

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