Very nice. Thank you for taking the time to explain. I learned a
couple new tricks!

So, the function returns the value from the result_vector that corresponds
to the *last* value in the lookup_vector that is less than the lookup_value.
The values in the result_vector are the column numbers: COLUMN(A1:H1).

I did not know you could specify COLUMN (or non-ranges) for the
results vector. Or is Excel seeing the COLUMN as a "range"? Can you
also specify an array of numbers for the results vector?

I remember seeing VLOOKUP can be used as an array or vector format,
but now that I'm looking in the Excel help file, I'm only seeing
references to the array format. Where does Microsoft document the
vector format?

Thanks again!