I've left a suggestion to Microsoft that they update their
description to say how the function REALLY works.

JC

On Mon, 13 Oct 2008 12:55:37 +0100, "Roger Govier"
<roger@technology4unospamdotcodotuk wrote:

Hi
If LOOKUP can't find the lookup_value, it uses the largest value
in the array that is less than or equal to lookup_value.

If you had an ascending series of numbers, then the above would be true

If the series is not ascending, Lookup is not trying to find the largest
(i.e Maximum value). It does not hold each value in turn and carry out a
comparison to see whether this is higher than the previous highest, it just
keeps looking down the list for the value chosen.
With that value being a very large number, and not likely to occur, Lookup
will return what is the last value it found in the list.

If dealing with text, then one looks for text that is unlikely to occur in
the column. That could be an unusual character, or say a string of Z's
=LOOKUP(REPT("Z",26),D3:D100)