Your GPSr should be able to handle three coord formats:
h ddd.ddddd° (degrees-decimal)
h ddd° mm.mmm’ (degrees minutes-decimal)
h ddd° mm’ ss.s” (degrees minutes seconds-decimal)
You should be able to enter in the coords for a waypoint in one format and then switch the GPSr to the other format.
The coords on geocaching.com are in (h ddd° mm.mmm’) – degree, minutes in decimal format.
h ddd.ddddd° is the position entirely in degrees – the minutes being represented by the fraction of degree.
h ddd° mm’ ss.s” is the position in degrees, minutes and seconds.
There are 60 minutes in a degree, 60 seconds in a minute.
These are all equivalent:
58° 39.225
58° 39 13.5
58.65375°
58.65375 degrees = 58° and (.65375 x 60 minutes)= 58° 39.225′
and
39.225 minutes = 39 minutes and (.225 x 60 seconds) = 39′ 13.5″
To go the other way:
58° 39.225 => 58 and 39.225/60=.65375 -> 58.65375
58° 39′ 13.5″ => 58 and 39 and 13.5/60 = .225 -> 58° 39.225
(If I did anything stupid here then at least I have an excuse for my DNF’s.)