This calculator is used to add and subtract angles in the form used in the Nautical Almanac, a publication with data used for navigation by ships. The angles in this publication are expressed in degrees in the usual way (0° to 359°), each degree is divided into 60 minutes, but each minute is divided into ten decimals (and not into 60 seconds).
The calculator adds or subtracts input values from the running total in the top window.
The decimal part of the minutes output is rounded to 1 decimal place to be consistent with navigation practice. However, the internal result is kept to the highest possible precision so that successive operations do not produce a cumulative error.
Whenever the calculator outputs a new result it also displays it in the Degrees - Minutes - Seconds format just below the main display window.
See also Degrees - Minutes - Seconds angle calculator.