Friday, January 27, 2012

How many different area codes are available using the digits 0-9?

An area code is basically a counter if you look at it in computer terms. Since 000 is a number you take the largest count you can place in the counter "999" and add "1".



If all the number combinations are use then there are 1000 possible combinations.How many different area codes are available using the digits 0-9?
None of the area codes in the US start with 0 or 1, so the first digit can only have 8 possible digits. This is because 0 is typically used for dialing the operator and 1 is the prefix for dialing a long distance number.



The second and third digit can use 0-9, so there is a possibility of 10 digits for each of those.



Thus we have:



8 * 10 * 10 = 8 * 100 = 800 possible area codes.



If you're allowed to use 0 or 1 for the first digit, then we'd have:



10 * 10 * 10 = 10 * 100 = 1000 possible area codes.

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