Good morning!

I need a formulate that calculates a value between a period of hours, which are being added daily 8 hours.
Ex: 11/02/2011 to 14/02/2011 instead of bringing the result 48 hours show 24 hours, which are the 3 working days.

Someone tell me if is possible?

Assuming that all dates are working days (as implied in your question), the formula would be

Where A1 contains the start date and B1 contains the end date.
The cell containing the formula should be custom formatted as [hh]:mm

That's exactly what I need. Thank you for your help.