Time Diff b/w two dates for minutes

Hi..Everybody

Can anybody help me to calculate time b/w two dates.....for example

Admit date                                   Discharge date                                   Time in minutes

1/5/2014  12:30:00 PM                  1/7/2014 11:30:00 AM                          35 hours

1/7/2014  12:30:00 PM                  1/9/2014 11:30:00 AM                           7 hours

1/11/2014  12:30:00 PM                  1/13/2014 11:30:00 AM                        12 hours

Thanks for advance......