How to calculate the number of working days between 2 periods

Excel has a worksheet formula called Networkdays. It's purpose is to calculate the number of days between 2 periods minus Sat and Sun in that period. What's more, you could even exclude holidays in your computation. Assuming that you have a holiday in that week (between Mon to Fri), the formula will return only 4 working days for that week. To find out more about this function, visit http://www.advanced-excel.com/date_functions.html#networkdays