Question

A zip-code is a five-digit number identifying where in the U.S. an address is located. The first four digits in a zip code can be any number 0-9, but the fifth digit cannot be 0. In addition to this, each address has a “plus-four” code that more specifically identifies the location of an address within a town or city. Similar to the main five-digit zip-code, the first
three digits in the “plus
-four” code can be 0-9, but the fourth digit cannot be 0.

a.)How many five-digit zip codes are possible in the U.S.?

Answer 1

9 * 10^4