Question

a realtor use a lock box to store the keys to a house that is for sale the access code for the lock box consist of four digit the first digit cannot be before and the last digit must be had how many different codes are available

Answer 1

Your question is somewhat incomplete but since i already know the question, i am solving it. The correct question is also given below. If you have any doubts, please comment

Correct Question:

A realtor uses a lock box to store the keys to a house that is for sale. The access code for the lock box consists of four digits. The first digit cannot be zero and the last digit must be even. How many different codes are available?

Solution:

There are a total of ten digits : 0,1,2,3,4,5,6,7,8,9

The problem told us that we cannot have the first digit of the code be zero -- this means there are 9 total choices for the first digit of the lock box code.

For the second and third digits of the lock box code, we are not told a restriction, and so there are 10 choices for each.

For the fourth digit of the code, we should pick any odd digit: there are 5 total choices here.

This means there are a total of

9 * 10 * 10 * 5 = 4500