Sorry if this has been covered elsewhere - couldn't think of of a search
keyword!

I'm working on rota. I've got a row for each hour, and a column for each
duty. In each column there are two numbers: a start time and a finish time.
But, of course, they won't be in the same rows.

I want to try out different possibilities and show the total time (start
time subtracted from finish time) under each column, without having to
specify the 2 cells every time I try a different arrangement.

Is there a way to do this? I should add that I'm not an expert coder, but
happy to cut and paste.