Whenever we played Axis and Allies in college, one of the tools that always accompanied the game was a calculator. Yeah, we really geeked out when we played, but what do you expect from physics students. So, I was kinda excited to see someone actually made an app to calculate the same sorts of things we used a calculator for. It is free too. There are other apps that do the same thing that are not free. This one comes with my recommendation.