Does anyone know how to project the due date according to a required number
of working hours? such as

If today is 24 Oct, 2005 (Monday) at 9:00am, my project required 100 hours
to be finished, then how to create a formula and to project the due date in
excel sheet?

Working hour: 9am - 1pm and 2pm - 5pm (total 8 working hour per day)

Thank for any suggestion
Eric