How to change hours worked on a project from 24 hr time to a decimal hr?

This is what I have: Cell O5 is clock in time, cell P5 is clock out time. They are both formatted military time, cell Q5 is total hours with simple formula =P5-O5  I want this to not be in time format though.

Example O5 is 10:30, P5 is 17:00, Q5 is 6:30, I want Q5 to read as 6.5 hrs so I can keep total of hours for the job at the end of these columns.