How to calculate a duration?

[Marco1212]

Hi everyone !

I ask for your help about how to calculate a duration.

FIRST : in the row “Date”, I wrote UTCNOW because I want to have a date+hour (MM/DD/YYYY HH:MM:SS)
Is it ok ?

SECOND : in the row “Calcul du Δt”, I want to calculate “Date” (row n) - "Date (row n-1)

Unfortunately, after many trials, I don’ t succed to program it…

Could somebody help me about this topic ?

Thank you a lot in advance and have a good day !