What I am trying to do is be able to lookup one number in Column A (Header is
WP), and give me all the matching results from Column B (Header is PMC), and
put display all the results in Column C. I need to do this without
downloading anymore addins also, thanks for your help in advance. Here is an
example:

WP PMC
1 1 1
2 2 2
3 3 3
4 4 4
5 7 7,8,9,10,52
5 8 7,8,9,10,52
5 9 7,8,9,10,52
5 10 7,8,9,10,52
5 52 7,8,9,10,52