Om het mezelf niet te moeilijk te maken, heb ik het volgende gewoon ergens opgezocht, de uitleg slaat op een formule die lichtjes verschilt, maar hetzelfde principe gebruikt.
This formula uses LOOKUP in its vector syntax form, with the lookup value as the
first parameter, the lookup vector as second, and the result vector as the last
parameter
The most interesting part of this formula is the lookup vector (the 2nd
parameter). The formula element
1/(1-ISBLANK(A1:A65535))
in this example returns the following array
{1;1;1;1;1;1;1;#DIV/0!;1;1;#DIV/0!;#DIV/0!;...;#DIV/0!}
that is, the ISBLANK function returns an array of TRUE (blank cell) or FALSE
(non-blank cell) values.
Subtracting this from 1 converts the array to an array of 0 (blank) or 1
(non-blank) values.
Dividing 1 by this array then returns an array of #DIV/0 (blank) or 1
(non-blank) values
The LOOKUP searches for the value '2' within the array (which now consists only
of '1' and #DIV/0 values). The LOOKUP will not find this value, so it matches
the last value that is less than or equal to lookup value. This is the last '1'
within the range which represents the last filled cell
This type of formula can be used for a lot of similar problems using the second
parameter to create a lookup vector consisting of either '1' or '#DIV/0' errors
by setting the Boolean expression accordingly