I apologize. I could not express my problem well. It is like that in first two columns, in every month there are more than 100 rows of date entries. To determine the difference of these two dates, for every month, I have to type/paste the NetWorkingDays formula in every rows of third column. My thinking is that can we automate this so that as soon as I enter a date in a row of second column(assuming that first row date column has already been entered), the third corresponding row column will automatically be filled in with a macro?

I would appreciate help from any of you!