Excel has a limited way of doing this.

In xl2003 menus:
Tools|Options|Edit tab|check "AutoComplete for cell values"

It uses the recent cells above the cell you're entering data as the list to
choose from.

If you only need this for a few entries, you may find that it's irritating to
toggle on/off.

You can rightclick on a cell and choose "Pick from drop-down list". It may be
sufficient for you.

bile wrote:

How do you order the computer to finish off words once you've begun typing if
it's come across them already?

--

Dave Peterson