Calculate Hours in SharePoint Calculated Column

It is a common formula for calculating days between two date column on SharePoint by using =DATEDIF([StartDate],[EndDate],’d), However there’s a date-time format on SharePoint column,e.g. 05/23/2011 7:00 AM to 05/23/2011 4:00 PM and we need to create a calculated column to count the difference in hour ? can we just use DATEDIF ? No , It won’t work! It is a little bit tricky but you could use the following function where…
[Start Time] column 05/23/2011 7:00 AM
[End Time] column 05/23/2011 4:00 PM
=IF(NOT(ISBLANK([End Time])),([End Time]-[Start Time])*24,0) -> it will give you 9 hour for differences

Multiple person on Assigned to column

When we create Assign to Column from SharePoint Task List, it only allow one person by default which means that only one person can received the email notification task. On some occation, we need to notify more than one person, in order to do this, you need to activate the “Allow Multiple Selection” on the assigned to column settings, it will allow more than one person separated by semi colon. Doing so, the e-mail notification will be sent to the listed people ( more than one person ).