Helipaddy's Apps let you work in any of the three latitude/longitude coordinate systems by simply selecting in the Account menu. The three systems are:
D : 51.1234 (sometimes called decimal degrees and not shown with the ˚ symbol)
DM : 51˚7.24.4' (sometimes called decimal minutes and common format of older navigation systems like Skymap)
DMS : 51˚7'24" (sometimes called DMS and the original format based on 1/60ths)
Many aviation documents and sites use DMS whilst all modern online mapping sites have adopted D. Note that all printed charts have DMS marker lines so the DMS format is useful for quickly finding a location. You may find you need to convert between the two. Actually you can quite easily do an approximate conversion in your head e.g. 51.5 is 51˚30'.
A converters we like is: http://www.pgc.umn.edu/tools/conversion
A degree of latitude remains fairly constant from the equator to the poles; however a degree of longitude can vary greatly as one approaches the poles (because of the convergence of the meridians.