HP -67 Owner's Handbook Manual page 99

Function Keys 95
Notice that the display is not automatically switched to show you
more than the normal two digits after the decimal point (FIX 2),
so to see the digits for seconds, you had to reset the display format
to FIX 4.
To convert from hours, minutes, seconds to decimal hours, simply
keyin the value for hours, minutes, seconds in that format and press
(2 (3. For example, to convert 132 hours, 43 minutes, and 29.33
seconds to its decimal degree equivalent:
Press Display
132.432933 132.432933 This is 132 hours, 43
minutes, 29.33 seconds.
0 This is 132.7248 hours.
(FIX 4 display remains
specified from previous
example.)
Using the and ({4 operations, you can also convert angles
specified in decimal degrees to degrees, minutes, seconds, and vice
versa. The format for degrees, minutes, seconds is the same as for
hours, minutes, seconds.
Example: Convert 42.57 decimal degrees to degrees, minutes,
seconds.
Press Display
42.57 Keyin the angle.
a This means 42°34" 12",
(Display assumes FIX 4
notation remains spec-
ified from previous
example.)