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## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: napier and logarithms
From: Michael Dorl
Date: 2009 May 28, 08:16 -0500

```corallina wrote:
> I finished reading "The Story of Numbers" by John McLeish
> chapter 12 is about Napier.  Unfortunately there is no mention
> of Briggs.
>
> On page 171 there is a description of how Napier calculated the logarithm
> of 2.  He raised 2 to the power of 10,000 which comes out to a
> number of 3011 places. He then subtract 1 from 3011 and gets 3010
> which is the logarithm of two good to 4 decimal places.  log10(2) = 0.3010
> I really don't understand why this works and hope somebody can
> explain it?
>

log (2**10000) = log ((10**0.30103)**10000) = log(10**3010.3)=3010.3

I still recall my calculus teacher telling us how he remembers log 2.
He thought of it as the ears, nose, and eyes of a face.  You have to
reverse the right ear though.

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