It's possible to calculate the distance between two points on earth, if you know the geographical latitude and longitude of both. In addition, it is possible to determine the direction (for example for aligning a rotatable antenna). The calculated values are accurate of 1 km and 1°.
Radio amateurs use the 6-digit locator to inform their interlocutors their exact location. Some ones uses the locator also in contests. With the following formular you can calculate the geographical latitude and longitude for a locator. In addition, you can specify whether the determined position is to be used for the formular above.
Note: If you use the 6-digit locator the calculated position is exactly only ±1.25′ in the latitude and only ±2,5′ in the longitude. This corresponds in Germany with ±2,82 km in latitude and with about 2,85 km in longitude. If you calculate the distance and direction between points on earth, you should consider this inaccuracy, if the both locater are close together.