[R-390] Slide rule calculations

[Bill Hawkins]

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