Countdown hours

[tommysidds]

I am trying to make a material out time countdown. I want to be able to place an X amount of hours in a cell and have it countdown to zero or negative values. For instance, say i have a material that has 230 hours left before it expires. I want to be able to put that value into a cell and when i refresh the spreadsheet it will be updated to a value. so say 24 hours later i get on and it should say 206 hours. I dont need to see minutes or seconds or anything, just hours. if you can help me out that would be awesome!!