AVERAGEIF across multiple tabs

[cafeaulait]

how can i do =AVERAGEIF(AZ6:AZ1721,">0",AZ6:AZ1721) but across 18 tabs all with the same ranges???

 

[T. Valko]

how can i do =AVERAGEIF(AZ6:AZ1721,">0",AZ6:AZ1721) but across 18 tabs all with the same ranges???

Will there be any negative numbers?

 

[T. Valko]

Will there be any negative numbers?

Assuming there won't be any negative numbers...

=SUM(Sheet1:Sheet18!AZ6:AZ1721)/INDEX(FREQUENCY(Sheet1:Sheet18!AZ6:AZ1721,0),2)

 

[barry houdini]

If you have a list of all the worksheet names, named Sheetlist then you can use this formula

=SUMPRODUCT(SUMIF(INDIRECT("'"&Sheetlist&"'!AZ6:AZ1721"),">0"))/SUMPRODUCT(COUNTIF(INDIRECT("'"&Sheetlist&"'!AZ6:AZ1721"),">0"))

Edit: that will work even if you have negative numbers but, if not, Biff's suggestion will be preferable