I suspect this is going to be very obvious to some of you, but how on earth does Excel decide that -00:13 added to 00:13 makes -00:00. I have a workbook set up with twelve worksheets each holding a timesheet for one month. They were all set up at the same time with the same formulas and Jan-Oct have worked just fine. I can solve the practical problem by pasting the values to a new sheet using the earlier sheets as templates, but I am curious as to how this kind of thing happens.
Thanks in advance.