Sum previous 8 rows

Thanks amitchandak,

I'm not sure it's a simple explanation but i will try! 

So we have a date, project number, total days (to complete project request), average days, days below average and then hopefully we can have a result. The hope is that we can look at the TotalDays in order of date created and if 8 entries or more are below the average days then we would mark in the result column the Total Days - this is what we call the run of 8. This in turn would allow us to highlight on a visual. So the desired outcome would look like the image below. Hopefully this makes sense? 

Thanks