I was referred to this website by a product expert in Google Docs Community Help center. I am trying to get the sum of the old value and the new value from the same cell. I'm dealing with numbers that constantly changes but I'd like to sum them all up instead of overwriting the cell data with the new data but only for data under column K. Here is a copy of the sheet I'm working on: https://docs.google.com/spreadsheets/d/1pArYf_651_6u1xpKUll94JIJ72V5ALdlOJ2bGQB6P_w/edit?resourcekey=0-uPU0RkaH5ntqYzKQMplXyw#gid=0
Screenshot In this screenshot, what I need is the Duration column to always refer its old value so that when it changes it will just sum the oldvalue + newvalue.
I've researched this site and found this Google Spreadsheet add same cell value. It appears relevant to my case but I can't quite add the onEdit trigger manually. Can anyone help installing the trigger? Also, can the function trigger for column K only?