Hi Adam,

LOOKUP ignores error values and returns the last non-error value if the
search value was not found.

1/(comparison) gives 1,1,1,#DIV0!,1,1,#DIV0!,1,#DIV0!,1... and if you
search any value 1 in here (i.e. 2) then you will get the position of
the last 1 - exactly what we need. Go into the formula editor and
evaluate this partially by selecting (comparison) and pushing F9, then
1/(comparison) and F9 again, etc.

[Not my invention, just my favourite question if somebody claims to be
an Excel expert :-) ]

Regards,
Bernd