I'm also looking at Conditional Formatting (to avoid having an extra line in the spreadsheet reading true or false). I now have something like =SUM(E5:E9)<E4 in conditional formatting. I'm stuck with the same error as before. What happens when I insert a new line of data, say E10, and I want to include that in my conditional formatting? And is there an easy way to apply the same conditional formatting stuff to other datasets, such as =SUM(F5:F9)<F4, etc?