Trying to create a user prompt for ClubNumbers but because it's numeric you can only enter one at a time.

I tried this with a parameter field set as String:

ToText({v060ClubOfficersClubAddress.ClubMbrNo},0,"") IN {?ClubMbrNo}

It does not work.

Thoughts/suggestions?

Yes and when attempting enter a few club numbers, it just produces no results and the numbers being entered do exist.

Without the parameter, you can go into the Report Select Expert and select the ClubNo field then do a IN as the type and from there add the ClubNo.
However we are trying to avoid the end-user from going there to do that and prefer user-prompts.