google spreadsheet - How does this formula to return the last value in a column work? -

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this formula returns last value in column:

=index(a:a;max((a:a<>"")*(row(a:a))))

can't understand how works because part max((a:a<>"")*(row(a:a))) returns 0.

any ideas?

for sake of answer. segment: 

=max((a:a<>"")*(row(a:a)))

returns 0 if row in has blank cell in columna, otherwise 1.

as array formula (ctrl+shift+enter before enter) get: 

=arrayformula(max((a:a<>"")*(row(a:a))))

returns row number of last populated cell in columna.

simplifying example of 3 rows first (row1) blank:

the 'not blank' part returns array of: false,true,true
, row part of 1,2,3

so multiplying (the *) these gives array 0,2,3 (multiplying false equivalent multiplying 0 , true equivalent times 1).

the max function selects largest value (3).

the index function 'reads' above return value in columna in last (third) row.


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