[R-390] Slide rule calculations

[Richard W. Solomon]

I remember a class I took at Northeastern University in 1958.
The instructor gave lessons on using a slide rule with a working
15' slide rule.
I remember he had to really push to get it to move and one time, 
before class, we chalked it up so it just glided.
He started in and gave it a shove and that middle piece almost flew
out the classroom door !!
At least he had a sense of humor.

73, Dick, W1KSZ

-----Original Message-----
>From: Bill Hawkins <bill at iaxs.net>
>Sent: Dec 5, 2008 6:20 PM
>To: R-390 at mailman.qth.net
>Subject: RE: Re: [R-390] Slide rule calculations
>
>Well, slide rules never caught on at banks. They are excellent for
>engineering
>estimates, where reality restricts us to 3-4 significant digits. Why the
>restriction? That was the accuracy of engineering measurements at the
>time.
>
>There's no fixed rule that results in 1/3 being zero. If the situation
>is
>such that only integers count, then 1/3 is zero. If the situation
>requires
>three digits to the right of the decimal point, then 1/3 is 0.333.
>
>Our R-390 class sets have 5 digit accuracy, with 3 digits to the right
>of
>the decimal. You can tune closer than that with a calibrated BFO.
>
>Bill Hawkins
>
>
>-----Original Message-----
>From: Barry
>
>> In the end, 3.12/9.7 is NOT 0.321649484536....    It is 0.32.  Digits
>
>> of precision in = digits of precision out.  This, of course, applies 
>> equally to sliderule calculations,  electronic calculator thingies, or
>
>> computers with 128-bit  or more floating point arithmetic.
>> 
>> Grant/NQ5T
>
>That's one of those rules that I first came across in college physics
>class
>and I struggled with it then as now.
>
>I understand basically why it is used, but by the same rule, is 1/3=0?
>
>Barry - N4BUQ
>
>
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