Question 1179092: In 2014, a certain state added a ninth area code. Using the information about telephone numbers below, how many telephone numbers can this state's phone system accommodate?
Telephone numbers in the United States currently have 10 digits. The first three are the area code and the next seven are the local telephone number. How many different telephone numbers are possible within each area code? (Note that at this time, a local telephone number cannot begin with 0 or 1.)
Solution:
Because the first digit of a local number cannot be 0 or 1, there are only eight choices for the first digit. For each of the other six digits, there are 10 choices.
So, the number of local telephone numbers that are possible within each area code is
8 · 10 · 10 · 10 · 10 · 10 · 10 = 8,000,000.
Answer by ikleyn(52786)   (Show Source):
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The solution is correct.
The logic is fine.
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Have a nice day (!)
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