In a chart, column G and L represent the entry and exit dates with the total
weeks of enrololment (difference) reflected in column S. I used the formula
=(L-G)/7 in column S. That determines the difference when columns G and L
contain dates. If G and L are empty cells, I get the VALVE error message.
How do I revise the formula to reflect a zero when column G and/or L do not
contain a date? Many thanks for the help.