GMFS - Geocaching Multi Formula Solver
Tool intended to help with Geocaching Multis, where you have to collect values in order to solve formulas.
Android app GCC offers a formula solver for geocaching, but I don't like it that much. Now there is a native app!
GMFS is packed with powerful functions. Check out the possibilities for importing a gpx file from geocaching.com (Premium membership only). Or else, just copy the geocache page into the import routine. I recommend WlanKeyboard or TinyEdit for this. Edit formulas and letters, and go!
Many calculations have been added, like intersections of lines and circles. Working with UTM or optionally with RD in The Netherlands. The WGS - UTM converter I found is OK for waypoint calculations, working with hundreds of meters, going from WGS ot UTM and back. However, the East converter in general is useless for real conversion from UTM to WGS.
BTW: I started using it for Mysteries as well, like the Bonus cache of a trail. Just one waypoint with the formula, and all letters to collect during the trail.