Where is my file?

Started a spread sheet in Numbers a few days ago. Opened it again tody by finding it on the list of recent docments, updated, closed. Just to check, tried to find it in Finder - can't. File name does not show up in spotlight.

If I open several more spreadsheets this one will get bumped off the list of recent documents, and them I am stuck.

Help! How do I find this file? Where is it?