Best way to find multiple matches

Hi all - first time forum user, thanks in advance for help.

I have several sheets in a workbook. The first contains the ID#s of anyone who attended a conference. The other sheets have the ID#s of new members. I want to see if ANY of the IDs at the conference match ANY of the IDs in new members.

So for example, I have NTPParticipants!E:E dedicated to the IDs of members who attended the conference. (Some are blank because not all attendees were members.) Then in FebNewMem!A:A are all the ID#s of new members that signed up in February. I want to know if anyone who signed up in February is listed on the NTPParticipants sheet, i.e. does any cell in FebNewMemA:A = NTPParticipants!E:E. (Then eventually does any cell in MarNewMem!A:A = NTPParticipants!E:E, and for april, may, etc.)

I've tried countif, countifs, index, match... not really sure what to use here. If I were only looking for a particular value or cell, maybe the ID#222111, then I would just use countif(FebNewMem!A:A,"=222111"), but this doesn't seem to be working when the criteria isn't a specific value or cell.

So what's my best option? Thanks!Participants vs New Members sample .xlsx