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    Re: The "golden rule of three" - what's that?
    From: Brad Morris
    Date: 2018 Feb 11, 18:54 -0500
    Tony

    It's just proportions 

    A/B = C/D

    Brad

    On Feb 11, 2018 6:27 PM, "Tony Oz" <NoReply_TonyOz@fer3.com> wrote:

    Hello.

    I'm reading the "History of Nautical Astronomy", Mr Cotter describes the state of (apparently insufficient) mathematical literacy of seamen of 15th century like that:

    ...importance in introducing to the English seamen ... the elements of mathematics beyond the golden rule of three.

    What is that?

    Recently I had some hard time guessing what the "butterfly multiplication method" is. We, in Russia, were never tought anything like that.

    Please comment.

    Regards,

    Tony

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