From the title I would have guessed

=AVERAGE((A16:A18)*(B16:B18))

which is an array formula, and is committed with Ctrl-Shift-Enter

but from the description I think you might mean

=SUMPRODUCT(A16:A18,B16:B18)/SUM(A16:A18)

which is not an array formula

--

HTH

RP
(remove nothere from the email address if mailing direct)


"hawsoon13" wrote in message
...
I am trying to get some square footages...I have a series of lengths in
one
column, and a series of widths in the next...I want to get an average
width
and multiply it by the sum of the lengths...the formula is
roughly...(A1*B1)/Ax:(A28+B28)/Ax...where Ax is the sum of A1:A28 in this
case...that formula obviously does not work...is there an easier way to
enter
this than to individually plug in every cell in a huge equation?...does
this
make any sense...thank you for any and all help...