You can't do it like that. Time calculations are much more complex than normal math calculations, and require a custom-made script.
There are good tutorials about this subject here:
Alternatively, if you don't want to write the code yourself, I've developed a tool that allows you to easily set up this kind of calculation, including the option to show the result in decimal format (ie, 2.5 for two and a half hours, instead of 2:30): Custom-made Adobe Scripts: Acrobat -- Calculate Time Differences in a Worksheet
However, I've run into another snag. Hopefully, it is a small fix. The Regular Hours cannot exceed 40 hours. Regular and Overtime should equal Total Hours Worked. What do I need to change to make this work?
This is the custom script for Regular Hours:
var normalHours = Number(this.getField("NormalHours").value);
var totalHours = Number(this.getField("TotalHours").value);
event.value = Math.min(normalHours, totalHours);
This is the custom script for Overtime Hours:
event.value = +this.getField("TotalHrsWorked").value > 40 ? (+this.getField("TotalHrsWorked").value - 40) : 0;
Change the last line of the Regular Hours calculation to:
event.value = Math.min(40, normalHours, totalHours);
Thank you very much. That worked.
I still have to devote some time to the other columns. I will look at the links provided and if I cannot figure it out, I will try your tool. I greatly appreciate the help.
I would convert all the in and out times to the number of minutes from the Epoch date and compute the time worked. I would use the "Format" tab to convert the number of minutes worked to the desired display format, since the displayed format does not change the value of the field. One then use the standard mathematical operators on the number of minutes without any changes.