I have a user that created an sales order form in excel.  He has an order
number that he must keep a manual record of and often duplicates the order
numbers.

What is the best way to automate this so that each time he opens the
spreadsheet the order number would increment by 1?

Since it is a blank form that the user opens and filles out the form and
saves it under another name, I could have a macro that when the form is
opened the serial number increments and save the file before the user enters
data.   Is that the best way?

DG