I use M$ Excel to help with project time-sheeting and billing. My bills are really simple and contain project id, project title and time spent in hours and minutes (h:mm). The project id and project title can be looked up on the issue tracker and filtered on the dates so there is no need to include all that lengthy information in the invoice. This produces a table of results. I have been trying to sum the time’s column, but each time it rolled over 24 hours it reset the clock and loss the information. For example 23:00 + 2:00 became 1:00 instead of 25:00. I had to count it up by hand, it was a good job I had to do all that time maths for my 11+! I had a bit of a hunt and found the solution on the Micro$oft knowledge base. Just do the summation as normal but format the cells to be in the format [h]:mm and the “h” part will handle the overflow. Simple in the end!