I had one in high school chemistry but I didn’t have it figured out then.
My oldest brother showed me how to use his slide rule while he was still in high school. Once I caught on that multiplication was just adding logarithmic distances, it made sense.
When I got to college in 1973, my freshman chemistry class voted on whether to allow calculators on exams. (I voted in favor, despite not having a calculator at the time.) The vote was “no”, so we all used slide rules and log tables. I got my first calculator, a Texas Instruments SR-51 II, a year or so after that.