Sum Times

Hello I am trying to set up a Clock In Clock Out Employee Hours function

Date Time Field for  TIME START.     and TIME END

and then using a Formula Field TIME WORKED. for calculating the time between TIME END and TIMNE START.

Now I would like to sum up each TIME WORKED for each of say, 7 days to calculate to the TOTAL HOURS worked, but it always returns a fraction of 24 hrs and never a true sum, like 49 hours.

Is there a workaround?    The TIMER field seems like we cant do too much with it except enter the date manually, which wont work - as we dont want the staff to edit their hours.