Try this. I assumed your range was A1:A10, change this to fit your data.
Enter this formula by using CTRL+SHIFT+ENTER as it is an array formula:

=AVERAGE(IF(ISNUMBER(A1:A10),A1:A10,""))


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Regards,
Dave


"KhaVu" wrote:

I used AVERAGE function in my spreasheet and received #DIV/0! error from it.
Is there a safe proof way to omit the invalid values out of the average
calculation.