ISNUMBER Formula Cleanup

[Wheelie686]

I have 365 columns, each representing a day of the year. So what I want is to average the last 8 Thursdays, then tomorrow I want to average the last 8 Fridays, Saturday will be the last 8 Saturdays... so on and so forth. The numbers are just straight numbers, they're actually pulled from other sources in the workbook so essentially they're formula results that will be 1 of 2 things.
1. Will be a blank as a result of a IF formula
2. A percentage based on dividing 2 other cells.


What I want is if any of the 8 cells are blank, I want to take a straight number from another cell. In the example below, it would come from OS8.
If not, then average the 8 cells.

As an example, I have the folowing.


=IF(AND(ISNUMBER(MO5),ISNUMBER(MV5),ISNUMBER(NC5),ISNUMBER(NJ5),ISNUMBER(NQ5),ISNUMBER(NX5),ISNUMBER(OE5),ISNUMBER(OL5)),AVERAGE(MO5,MV5,NC5,NJ5,NQ5,NX5,OE5,OL5),OS8)

What I'd like to know is if there is a way to simplify the formula so I don't have 8 ISNUMBER parts.

[Phuocam]

Try:

=IF(COUNT(MO5,MV5,NC5,NJ5,NQ5,NX5,OE5,OL5)=8,AVERAGE(MO5,MV5,NC5,NJ5,NQ5,NX5,OE5,OL5),OS8)

[Wheelie686]

Hmm that seems to have done the trick. I would've thought the blanks would've counted. Thanks!