Military/24 Hour Time Adding and difference finding

I have a spreadsheet with a lot of raw data that I need to separate and make statistics with.

Basic columns are: Name, Event, Time Start, Time End

I need to see how long someone was at an event. I can do this with simple math, but the problem comes that I am using 24 hour clock to do this. The times only come in 30 minute intervals. I have two problems...

1) I need to add the total time someone has been at all of the events.

2) I need to know how long they have been at one event first, including if it starts at 1700 and goes until 0200.

An example spreadsheet is below.





Worth noting is that there are consistently more rows being added by the day or week.
Thanks.

In E2 and copy down,

=(DOLLARDE(D2/100, 60) - DOLLARDE(C2/100, 60))/24 + (C2>D2)

Format the result as [h]:mm

You're welcome, glad it worked for you.