In article , "Mr.
Luddite" says...

I was down in the basement going through some boxes of junk and came
across my K&E sliderule that I used back in high school while taking a
drafting course. I was never very proficient with it, but I
remembered how to do basic functions like multiplying a couple of
numbers.

So, my 15 year old grandson showed up at the house. I handed him the
slide rule and asked him if he knew what it was.

Not a clue. He played with it a little then handed it back asking
what it was.

I explained it was a slide rule and, if you knew how to use it, it
could solve very complex math problems.

He said, "Cool, but I can do all that on my cell phone".

My brother used a slide rule in college, and I did some in high school.
He bought a T.I. calculator, that could add, subtract, multiply, divide
AND do square roots! We were amazed with it. My uncle just couldn't
believe it!!