Question 547666
Okay so we have ___ ___ ___ ___ to fill in.  

Since the number is even, the last blank must be an even number (0,2,4,6,or 8).  So there are 5 choices for the last blank.  

For the first blank, we cannot have a 0 (as it would not be a true 4 digit number) and we cannot have the digit that was already placed in the 4th blank.  This means we have 8 options.  

For the second blank, we can now have 0, but we cannot have either of the two numbers that have already been placed.  This means we have 8 options.  

Similarly, for the third blank we cannot have any of the other 3 numbers that are chosen so we have 7 options.  

Using the product rule we get that there are {{{8*8*7*5=2240}}} options.  


Hopefully this helps, let me know if you are still unsure.