Houston has 3 area codes. How many phone numbers are possible?

Using standard calling rules of course. Meaning no phone numbers starting with 0 or 1.Houston has 3 area codes. How many phone numbers are possible?
3 area codes means you can multiply the final answer by 3.



there are 10 integers that we can use, 0 through 9. (0,1,2,3,4,5,6,7,8,9)



the first number has 8 choices since we can't start with 0 or 1. You CAN, however, repeat numbers. Therefore there are 10 options for all the rest of the digits.



so therefore

(8)(10)(10) (10)(10)(10)(10)



which is 8*(10^6) = 8,000,000 possible combinations per area code. Since there are 3 area codes, we have 8,000,000*3= 24,000,000 total possible phone numbers.Houston has 3 area codes. How many phone numbers are possible?
3 area codes X999,999=2999997

facebook.com