Dear Sir/Madam

This is at a school. I worked on an invigilation timetable. everything else very fine except the total hours spend by each teacher invigilating. I have a query in which I have the duration of each examination from the following function

Format([Start_Time]-1-[End_Time], "Short Time")

Now what I am after is another expression or function that I can use in another query to add up the hours and minutes spend by each teacher invigilating exams.

Gots