Is there any formula to calculate dates and times. I would like to input a
start date then input an end date and have a formula that will calculate how
many days/weeks/months have passed (this would have to take into account leap
year). I would also like to do this for time. Input start time and end time
and calculate how many hours/minutes/seconds have passed. Finally input a
start time such as 1:00 pm add 45 minutes and have the answer be 1:45 pm.

Any help would be appreciated.