A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
For the minimum value (excluding blanks), use the following array formula, confirmed with Ctrl+Shift+Enter:
=LOOKUP(2,1/(IF(A10:A999<>"",COUNTIF(A10:A999,"<"&A10:A999))=0),A10:A999)
For the maximum value (excluding blanks), use the following array formula, confirmed with Ctrl+Shift+Enter:
=LOOKUP(2,1/(IF(A10:A999<>"",COUNTIF(A10:A999,">"&A10:A999))=0),A10:A999)
This won't work for zip codes (probably).
The algorithm used by Excel to populate dropdown lists is not available to us users.