As far as I can tell, all LOOKUP functions require you to know a specific search_key (like a column or row header) in order to search for and retrieve a relative value.
Inversely, is there a way to find what the search_key is if you only know the value?
So, for example, if you have a matrix of values, how would one search through the matrix of unique values and return the column header?
a|b|c|d 1|2|3|4 5|6|7|8
What letter column is the number 7 in, for example?