Assuming you want some indication

=IF(OR(C8="",L8=""),"Dates incomplete",(L8-C8)/7)

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HTH

Bob Phillips

(remove nothere from email address if mailing direct)

"Jack" wrote in message
...
Cells C8 and L8 represent entry and exit dates. I used the formula
=(L8-G8)/7 to find the number of weeks between the dates. This works when
there are dates in cells C8 ands L8. However, when the cells do not
contain
dates, I get the VALVE error reading in the cell designated to show rthe
number of weeks. How can I modify the formula to address instances when
the
cells will be left empty?

Thanks