See http://word.mvps.org/FAQs/MacrosVBA/NumberDocs.htm .

Also see http://word.mvps.org/FAQs/MacrosVBA/NumberCopiesOf1Doc.htm .

The two replies posted are excellent solutions to your problem. My only
concern is that they require some experience with writing Macros/Subroutines
in VBA, which is not a common skill.

I would like to create some options that may be less graceful, still get the
job done, but without a need for a VBA solution.

One option is to move out of Word. I can envision your boss wanting to track
the different gift certificates that were issued like the date they were
issued, the salesperson who sold it, maybe a name of the individual who
bought it or to whom it would be given. Then your boss could track when gift
certificates were redeemed, how many were still outstanding (not redeemed),
which employee sold the most for a nomination as employee of the month, etc.
If your gift certificate program will grow like this, I would recommend
building a gift cerfiticate database in Access. You would probably have to
rebuild the certificate as a report, but you can use the AutoNumber feature
of Access to generate the gift certificate numbers on the certificates that
you print out. This doesn't eliminate the need for new skills, just replaces
VBA with Access.

Maybe a less daunting option would be to set up your Word document as a Mail
Merge. You could insert a field for the record number, Add 100 empty records,
to start at your boss's magic number. Then when you needed to print a new
certificate, add a record and print the certificate for that record only.
You'll want to read up on Mail Merge and practice some. It is very easy to
print all of the records, and I don't think your boss will want to pay for
all that paper.

I haven't tried it, but you may be able to merge your gift certificate with
an Excel Spreadsheet. In the spreadsheet enter 100 in the first box (Cell).
Below it type "=A1+1" When you hit Enter the value 101 will appear. Copy this
"formula" down the rest of the column and here is your sequence of numbers.
Next you'll want to try to Mail Merge your Word document with this Excel
spreadsheet. Use this column as your Mail Merge field. Again practice with
the Mail Merge because it is easy to print every numbered certificate from
the spreadsheet.