Ah yes, I still keep a 6 inch slide rule on my desk at work, Some of the younger people will ask what kind of a ruler that is with aall those markings on it. The head QC guy got all upset that I had a ruler with no calibration sticker on it. I have to explain that it is not a ruler for measuring, it is my old pocket calculator, way back, I kept the big 16 inch calculator on my desk.
Yes I remember paying $100 for my first pocket electronic calculator that could only add subtract multiply divide and percent.
I used HP for so long, Still do, I still use RPN for the calculator I have in my phone, That really messes with people IF I let them borrow my calculator.