You can buy scientific calculators before smart phones that graphed functions .I had one .I had to use it for a few math classes in college .This brings up another memory. We were not allowed to use calculators in high school. Everything had to be done by hand and we were required to show our work so the teacher could tell if we used a calculator or not even at home.
Ten years after I graduated from high school, I enrolled in a technical institute automated systems maintenance program. This was a 2-year program that touched on many topics including Integrated Circuit (IC) board level electronics, electrical motor control circuits, conduit installation and bending, hard-wiring relays, switches, photo sensors, capacitive sensors, and actuators, Programmable Logic Controller (PLC) programming, Computer Numerical Control (CNC) programming, pneumatic and hydraulic controls, National Electrical Code (NEC) study, and technical writing.
When analyzing IC board level electronics we worked with very small numbers, sometimes carrying up to 12 places past the decimal point. At that time the only calculator I had was a solar powered simple math calculator. It had minimal functions including add, subtract, multiply, divide, square root, and maybe inverse but that was it. I was about 30 years old then and of course most of my classmates were fresh out of high school. To work with those small numbers, I used scientific notation along with my simple calculator to solve the problems. My younger classmates were amazed. Apparently this was no longer taught in schools so it was new to them. It would have been about the same for me if someone was using a slide rule for I was never taught how to use one of those. I almost made it through both years of the program using that simple calculator but eventually had to break down and buy a new Texas Instruments TI-35 because it was getting too difficult to complete the math work on my tests in the given time allowed. Today, the calculators on our phones are far more capable.
Algebra,and business calculus and statistics. It was a must in class for the calculus.