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    Re: Getting ready for a spring demo...
    From: Gary LaPook
    Date: 2013 Dec 29, 22:01 -0800
    3600 is the approximation for rifle shooting, one inch at one hundred yards (3600 inches) is approximately one minute of angle.


    From: Frank Reed <FrankReed@HistoricalAtlas.com>
    To: garylapook@pacbell.net
    Sent: Sunday, December 29, 2013 6:47 PM
    Subject: [NavList] Re: Getting ready for a spring demo...

    "use 3600 instead of 3438, it's easier to do The math in your head."
    Well, sure. :)
    You memorize 3438, then if you're working in your head and don't have a calculator nearby, replace it by whatever is convenient. In one circumstance 3600 might be convenient, in another 3400 might be convenient. Heck, even 3000 is fine for a quick estimate. But memorize a value that's as close as possible within the constraints of the usual problem of memorizing anything. Back in the 18th century, Nevil Maskelyne usually quoted 3437.75.
    All you need is ONE "magic number": 3438.
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