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<span>I took Thermodynamics is a classroom with a 6 foot wooden slide rule suspended above the blackboard. The instructor would always estimate the answer before he brought the slide rule into play. He estimate was usually within 10% or less of the slide rule
calculation.</span></div>
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<span>He would use 10 as a value for pi squared.</span></div>
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Scientific calculators were still 10 years from affordability for personal use.</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> AT <at-bounces@lists.antique-tractor.com> on behalf of Carl Gogol <cgogol1971@gmail.com><br>
<b>Sent:</b> Friday, March 6, 2020 9:21 AM<br>
<b>To:</b> 'Antique Tractor Email Discussion Group' <at@lists.antique-tractor.com><br>
<b>Subject:</b> Re: [AT] Supposedly why our old tractors are not metric and a fairly simple tutorial</font>
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<div class="PlainText">The context I learned 22/7 was in high school math. Lots of simple problems<br>
could be built around it. I have never heard of the 355/113 version.<br>
Carl<br>
Manlius, NY<br>
<br>
-----Original Message-----<br>
From: AT <at-bounces@lists.antique-tractor.com> On Behalf Of Roger Moffat<br>
Sent: Thursday, March 5, 2020 8:34 PM<br>
To: Antique Tractor Email Discussion Group <at@lists.antique-tractor.com><br>
Subject: Re: [AT] Supposedly why our old tractors are not metric and a<br>
fairly simple tutorial<br>
<br>
<br>
<br>
> On Feb 25, 2020, at 9:58 AM, Stephen Offiler <soffiler@gmail.com> wrote:<br>
> <br>
> Just a matter of significant digits. 22/7 is about 0.04% higher than the<br>
"true" value of pi. That's pretty darn good for many practical purposes,<br>
but I wouldn't want to be calculating a moon launch with that kind of error.<br>
<br>
An even more accurate, easy to remember value for pi is 355/113 (or 113<br>
divided into 355)<br>
<br>
22/7 = 3.14285714<br>
pi = 3.1415926535<br>
355/113 = 3.14159292<br>
<br>
Cheers<br>
<br>
Roger<br>
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