A telephone number consists of seven digits, the first three
representing the exchange. How many different telephone numbers are
possible within the 537 exchange?

Hi monkadeen-ga,

Of the seven digits, the first three are used to represent the
exchange. Therefore, the remaining four digits denote the telephone
number within the exchange.

In your example, the possible telephone numbers within the 537
exchange are numbered from 537-0000 through 537-9999. Therefore, there
are 10,000 possible different telephone numbers within the 537
exchange.

Regards,
eiffel-ga

What formula would you use to calculate this probability.