Abacus

[Tybee]

I used a slide rule in high school. I remember there was a song with slide rule in it, the Sam Cook song "What a Wonderful World."

[jp1]

I was the last class in high school physics to use slide rules. After my year, calculators were allowed. I am pretty good at rough guesses on numbers, and getting the order of magnitude correct. Its a useful skill.

My high school chemistry teacher allowed calculators but also insisted that we learn how to use slide rules because ‘sometimes batteries die, etc’. After that class the slide rule went in a drawer and today I would have no clue how to use one.

[LDAHL]

This should be right up LDahl’s alley. Didn’t he work daily with those before retiring?

(just kidding you, Ldahl.)

We had efficient modern computers as long as you didn’t bend the punch cards.

[jp1]

I used to have a pro-rata wheel just like this at work. (it's used to calculate part year insurance premiums). Unfortunately I seem to have lost it when we moved last fall. Honestly using it is as easy as using an excel worksheet made for the purpose. And if I need to calculate a short period of time like two weeks it's even easier just to use a calculator to divide the annual premium by 365 and multiply that by 14. A pro-rata wheel only becomes useful if one needs to calculate premium for a period where the number of days is not immediately obvious.

prorata.jpg

[rosarugosa]

JP: I used to use one of those at work to calculate follow-up dates for employees who had temporary work authorizations.