Lookup the Least Frequently Occurring Value

Returning the Least Frequently Occuring Value

The following formula returns the least frequently occurring value from A2:A10...

=INDEX(A2:A10,MATCH(MIN(COUNTIF(A2:A10,A2:A10)),COUNTIF(A2:A10,A2:A10),0))

Note that the formula needs to be confirmed with CONTROL+SHIFT+ENTER. If done correctly, Excel will automatically place curly braces {...} around the formula.

Based on the sample data, the formula returns "D".

Sample Workbook: Download