is there a way to find all numbers docs?

Is there a way to find all documents made with Numbers?

Lost a tax document I was working on ... if I could just do a search query for all docs made with Numbers, it would help, as I don't use the app much.

For example, most Photoshop docs end with a .psd suffix or something similar. But Numbers doesn't have anything.

Feeling rather silly. Not a new sensation at all.