I have an Excel workbook (call it Workbook A) with one worksheet for every
day of the year since July 1, each containing, among other things, a list of
order numbers for that day.

In another workbook (Workbook B), I have a smaller list of order numbers.

What I would like to do is write some kind of function in Workbook B so
that, for each order number in the smaller list, it will look for that same
order number in Workbook A (it could be in any worksheet in Workbook A) and
return the name of the worksheet -- the date for the order.

Does such a function exist?

Many thanks for any help.