I have never needed calculus since leaving university, nearly 40 year ago. If you're not in hard engineering, you probably won't (and if you are, you'll get to use all the computer assisting tools you want).

Math in general is something that you don't need to know until you need to know it, the problem with "just in time" learning is that if you don't already know it then you won't even be able to know when it's needed and which specific bits of math you need to learn for the specific situation you find yourself in.

If you don't know math, you often won't be able to even realize when math is needed.

There's a Steve Yegge quote about this:

> You'll gradually realize that your math deficiencies aren't just something that you might need to beef up on if you ever "need to"; you'll see that virtually every problem space has a mathematical modeling component that you were blissfully unaware of until Done, and Gets Things Smart gal points it out to you and says, "There's an infinitely smarter approach, which by the way I implemented over the weekend." You stare slack-jawed for a little while, and then she says: "Here's a ball. Why don't you go bounce it?"

If you overly rely on the computer assistance during the learning stage, there are fundamental principles you won't get a firm grasp on, and then you'll be at a disadvantage if you need it later. As someone who did use calculus after school, I'm glad I actually learned the subject.

You're right that most people don't need to know calculus in their lives, but to my knowledge calculus also isn't generally required to get through college/university for most people, so it's fair to assume that the people in the course are there because they need or want to learn it. When I was a TA for calculus, most of my students were pre-med, engineers, or in other sciences.

> if you are, you'll get to use all the computer assisting tools you want

I've done work on fluid simulations. It sure would have been nice to understand the buttons being pushed so I can better validate what's going on.

And I think I did well in calculus. Just not "mastery of multi-variable calculus to transform fluid dynamics formulas into software" well.

Calculus can get pretty heavy, but I really value the comfort it gave me of the concepts of velocity and acceleration, (not to speak of higher orders) of which I am sure I wouldn’t understand nearly as well without the calculus background. I’m sure for most of HN velocity and acceleration, etc seem like super basic concepts, but I just don’t think I could apply the mental models as easily as before I took calculus.

That's wishful thinking. I have been placed into professional situations where I needed calculus and, as I found out to my sorrow, all the CAS software packages in the world wouldn't have helped because I didn't have/remember enough math fundamentals. The CAS cannot provide any kind of answer if you don't know how to ask it the right questions.