Hey all!

I'm trying to make a timesheet to log my flight-hours.
I've prutty much managed to make it like I want to, but a few function is
missing.

Ex 1)
Takoff-time 12:00 Landing-time 12:59 = Total flight-time 00:59
How do I manage to get Total Flight-time rounded to the nearest 5min? It's
nopt a problem with numbers, but time i can't find out of.

Ex 2)
I want to make the sheet sum every 18th cell and post it at another spot
saying:
Page1 50h
Page2 36h
Page3 19h
etc.

Is there a formula that can do this for me. or do i have to Type
Page1,Page2..... and then in then next cell sum every 18th cell manualy?

Hope someone can help me

Yours
Morten