I expect what you are talking about are Universal Transverse Mercator grids that the military uses. This is a grid system based on a metric grid. You should learn to use it and forget about Lat and Long. This is because degrees of longitude are indefinate, they have no fixed size, they change depending on your latitude. The last digit of either north or east of a UTM coordinate represents 1 meter. The next to the last represents 10 meters and so on.
Because there is a definate value to these numbers, I was able to scale off a distance and direction on a map from my ice house to a little underwater hilltop, and then convert those numbers into a UTM grid and then use my GPS to get very close . There is no way I could have done that using Lat and Long.