I have a spreadsheet I use to track tasks for my branch. All the information
is in a list.
Column C is due dates [starting in row 3]
Cell J2 is the function =TODAY() [outside of the list]
Column E is days left until due via the formula =-(J$2-C#) [starting in row
3]
Column D is either "Open" or "Closed" depending if the task is complete or
not. This column is manually changed and is always spelled exactly the same
thanks to predictive text.

What I would like is when Column D is changed from "Open" to "Closed" that
the value in column E stops changing.
This would allow me to see how early or late tasks are completed. Thank you.