Question

here are 680 three-digit numbers that are available for use as area codes in North America. As of April 2010, 301 of them were actually being used (Source: www.nanpa.com). (3 pts.)
a. How many additional three-digit codes are available for use? 379
b. Within a given area code, how many unique telephone numbers are theoretically possible?
c. As of April 2010, how many total phone numbers are possible in North America?

Answer 1

there are 1000 possible numbers because there are that many numbers from 000 through 999

within each area code is a seven-digit number, so how many can that be?

Answer 2

I mean 1000 possible area codes between 000 and 999