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Logarithms before 1965

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Date: 02/08/99 at 16:16:22
From: Nicole
Subject: Logarithmic Use before 1965

Could you tell me how logarithms were used before the year 1965?
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Date: 02/09/99 at 08:45:33
From: Doctor Peterson
Subject: Re: Logarithmic Use before 1965

I'm not sure where the date 1965 comes from, but I suspect it's being
taken to represent the beginning of electronic calculators. I was in
high school not long after 1965, and calculators didn't exist as far
as I was concerned; when I entered college in 1970, every engineering
student still needed a slide rule.

We learned how to use logarithms in at least two ways. First, we had
tables of logarithms that we used to simplify complex multiplication
problems. For instance, in a simple case you would look up the
logarithms of the numbers you want to multiply; then you would add the
logarithms and look up in reverse to find the number whose logarithm
that was, which gave the answer. There were also tables of logarithms
of trigonometric functions, so you could save a table lookup when you
had to multiply. You had to learn a lot of tricks to use logarithms,
such as how to look up a number between two numbers in the table
(interpolation), and how to figure the log of any number from a table
that gave logs only for numbers from 1 to 10.

Second, the slide rule is based on logarithms: the distance of a number
along the rule is the logarithm of the number, and numbers are

Calculators mostly eliminated both uses of logarithms. Occasionally,
it can still be useful to use logs for calculations, when numbers go
beyond the range of a calculator.

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http://mathforum.org/dr.math/problems/temple.7.12.96.html

- Doctor Peterson, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Logs
Middle School Logarithms

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