@ Space Coast Flea Market
Port St. John, FL, USA
These were still being used while I was in high school.
I remember attempting some cos(i) problems in algebra.
Fun and interesting.
The seller of this piece said he started out as an engineer major and used one of these.
He didn't say if this was the one he used.
While in college the big engineering calculators started coming out.
I often wondered if someone proficient in the use of a slide ruler,
could get an answer faster than someone using the calculator?