The same three digit prefix is used for all of the telephone numbers in a small town. How many different telephone numbers are possible by changing only the last four digits?

1 Answer
Oct 11, 2017


10000 possible numbers


If you are allowed to repeat numbers then we can use the fundamental counting principle:

There are four slots for possible numbers and there are #10# possible digits.

So there are #10*10*10*10=10000# numbers