I was hoping this article was going to introduce calculus using financial derivatives in practical examples. Instead the article asks how would one extimate 4.

I was hoping this article was going to introduce calculus using financial derivatives in practical examples. Instead the article asks how would one extimate 4.1 squared without a calculator. I can't recall of any time in my life when I needed to do so. Now that I have a smart phone and watch, I don't anticipate needing to do so any time soon.