Question 126821
Depends on whether you can repeat digits or not.


If you CAN repeat digits:


The first digit can only be 2, 4, 6, or 8, so there are 4 ways to pick the first digit.


Then there are 10 ways (0,1,2,3,4,5,6,7,8,9) to select each of the remaining 3 digits.


So the total number of 4 digit numbers under these conditions is:
4 X 10 X 10 X 10, or 4000.


On the other hand, if you are NOT allowed to repeat digits,


There are still the same 4 ways to select the first digit, but now there are only 9 ways to select the second digit because the selection for the first digit was eliminated from the selection pool.  Likewise, there would only be 8 ways to select the 3rd digit and 7 ways to select the 4th and last digit.


So the total number of 4 digit numbers under these conditions is:
4 X 9 X 8 X 7 = 2016.