A free app for Android, by Eisbehr.
The GeoCache Calculator is a tool for calculating values and checksums based on tables. It is designed to work on many platforms and devices, and is fully compatible with Android, iOS, Mac, and Windows. It contains over 250 different functions.
You can use it for calculating checksums and other values, such as coordinates, distances, areas, volume, weight, temperature, pressure, and many more. It also supports tables for supporting your outdoor geocaching search.
It has an extensive help section with many examples and tips, which will help you use the tool better.
