I had a reply from JimHess (thank you Jim) but it's not showing here for me.
If you can see this Jim - no, I'm not looking to find a photo by its 'real name' or anything I've assigned to it. When I'm in the Library of LR in grid view, all of the photos have a large number in pale grey font at the top left of their dark grey 'frame'. I was hoping to be able to go off into a collection or something and then come back to Library Grid and type the last number I'd looked at before to get back to the spot I was working.
If I was looking in small collections or folders it would be fine, but I'm sorting the entire 41,000 photos already on my harddrive when I first bought LR a few days ago. Using the side scroll bar to get back to the spot when I had been before is not working well for me.