=AVERAGE(IF(NOT(ISNA(A1:A15 )),A1:A15))

which is an array formula, so commit with Ctrl-Shift-Enter

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HTH

Bob Phillips

"hongkonglt" wrote in message
...
I perform a lookup where the results could populate one cell or as many as
15
cells with number results. The cells that do not result in numbers have
#N/A. I want to average the fifteen cells but only the cells with
numbers.
How do I get it to ignore the #N/A when performing the average?