Circa 1967, in physics class we used slide rules. One always knew who was a science nerd. We had a slide rule poking out of our shirt pocket or a really good one hanging off our belts. The really good ones were to big for a shirt pocket.
Mine was the big one. It had a really nice leather pouch and it was my Dad's until he gave it to me. I was the only one of his four children to take the hard math and science classes so I got his slide rule.