Question

14. All phone numbers consist of a three-digit area code, a three-digit exchange, and then a four-digit number. A town uses the 587 area code and the exchange 355; for example, 587-355-1234. How many different phone numbers are possible in this town under the following
conditions?

a) At least one digit repeats in the last four digits of the phone number.

Answer 1

ANSWER

9000

=  1 X 1 X 9 X 10 3 = 9000