As an intern over the summer I used calculus on an almost daily basis (But that might be because I am a Economics major and had the internship in a related industry) It is really helpful for finding industry surpluses, elasticity and probability given certain constants.

Depends on what gun show you go too, what state it is in and who hosts it. There was a very good gun show about 40 miles outside of St. Louis that had a great selection. The local conservation department had a guy there who would help you find the best gun/caliber for what you were going to hunt. I talked to him for over an hour about the drop in hunting popularity recently. But it has been cancelled for the last two years due to COVID. In short, there are many factors that make a gun show good😎 or not.