Need to calculate a future date

In Calc, I need to calculate a date that is a period of days in the future. Example if the dates 07/19/2012 6:48 I need to calculate what date time is 20 days, 12 hours, 10 minutes and 36 seconds from that time.

I can not figure out how to do this.

Try to add DD+(HH+(MM+SS/60)/60)/24

Thank you very much for your response worked perfectly