Question

PLEASE HELP The ZIP code is a 5-digit number that is unique to a specific region of the country. If the digits 0-9 are used, how many ZIP codes are possible with 0 as the last digit? Note that, in this case, the first digit can't be 0.

90,000



18,000



10,000



9,000

Answer 1

9000

Explanation:

The first digit can't be 0, so there are 9 numbers that can be used for the first digit. The fifth digit must be 0, so there's only 1 number that can be used. The other three digits can be any of 10 numbers.

So the number of zipcodes is:

9 × 10 × 10 × 10 × 1 = 9000