Thanks for your response, Chris! I think you've got me on the right track!  But I'm not quite there yet.  I have an email reporting to me that there is a missing number (test run was on Cheque #'s 25126 to 25140 and there are two missing cheques, 25127 and 25129.  For some reason, it is only reporting to me about #25129.  What might I be doing wrong?

My experiment is using just the second half of what you showed above.  I did not even need an Excel spreadsheet.  I just put a cheque number in a metadata field on a specific folder (target test folder) for the repeat activity to grab each round.  At the end of each run through, it changes that field number to the next number (plus one) for it to grab at the top of the repeat activity each round.

I'm wondering if it's due to the token configuration in the email:

Can't quite tell from the picture.  If its only showing you the last one, are you updating the missing token values with and append or replace?  Only getting the last one usually means replace, make sure it is append.

Also, move your track tokens to the very end of the workflow outside of any loops and run it again.  Then check your token tab in the workflow designer.  Does your missing number token hold both numbers or just one?

Chris, my Assign Token Values window looks different from yours and doesn't have the option for Append to existing values.   ??

That is because you are in the create token area and not modify.  You want to create the missing numbers token first and then update it.  Create the missingnumber token up in the same Assign Token Values activity as your starting and ending numbers (above search).

In your Missing branch, your Assign Token values is creating the token.  It should be modifying it.  Instead of Create, pick Modify.

Then select the MissingNumbers token up in the Assign Token Values activity.  It should read something like MissingNumber: Append 

Okay, then.  Learning things today!  So, I made the changes and tried again.  Now the email coming to me is blank.  Here is what I have now (just clipped the pertinent parts):

And now I've tried this and the email only gives me the last number it was to check on:

Will have to leave the office now, but I'm close!  It's now tracking the numbers correctly and finding the right results correctly, but the Missing Numbers token is coming up blank!

The missing numbers shows it did find the two missing numbers correctly, but the email does not reflect the two numbers:

Also tried the semi colon:

Its most likely empty because it is not appending and the last number found was true.  The multi value token should appear like my screenshot above as one token with multiple numbers.  Your token list shows the missing number multiple times.  I am not certain if it is the retrieve fields (in my example the check number is in the field but notice I am not doing the retrieve fields) or the order.  Maybe just hard code in your first check number?  If you build it out like the example it should work for you.

When I tried hard coding in the first cheque number (last thing I tried yesterday) the result was that it ran through the process once and did not continue through repeating the steps with each incremental number.