I'm confused about how time is computed in the Time Clock when a staff member works a partial hour.

The clock recognizes minutes as a portion of an hour and computes them accordingly.  Example:  Sarah clocked in at 3:46 pm and clocked out at 4:04 pm.  She worked 18 minutes; so Jackrabbit calculates the partial hour as 18 minutes / 60 minutes and displays the result as .30 (18 / 60 = .30).