I'm having trouble figuring out what this question is asking for:

"Complete the following circuit so that the 7-segment indicates how many of the four numbers are even."

Here is what she has given us:

 

Take an even number (4 bit binary) and an odd number. What distinguishes them?

 

So, would it be even, odd, even, odd and so forth?

Here is what I mean:

A B C D Y
0 0 0 0 1
0 0 0 1 0
0 0 1 0 1
0 0 1 1 0

 

This problem is just a bit more complex than the other - http://forum.allaboutcircuits.com/showthread.php?t=36759

Solve the other problem, which is very simple. You have everything for it but the answer. Then figure a way to deal with the above problem.