This is what you have to do:
Latitude: 38º 51′ 00″ N
Longitude: 0º 07′ 06″ W
- Take the seconds (“) and divide by 60 so you get the minutes.
- Add the resulting amount to the minutes
- Take the minutes (‘) and divide by 60 so you get the decimal part.
For the example above,
Latitude becomes 38.85
Longitude becomes 0.118333
You can also do it in this website: http://transition.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html