converting ºC to ºF or ºF to ºC

David Ehrlich
Tue, 10 Feb 2009 11:05:15 PST
Well Adam, yes and no.  Do the arithmetic yourself; you'll find that your adding or subtracting 32 before or after multiplying or dividing by nine-fifths is much more difficult to remember and yet gives the same result as my easy-to-remember symmetric formula.  My formula is based on a mathematic result, namely that when a domain is mapped into itself 1-to-1, there will be a fixed point.  In the case of Franenheit and Celsius, that point is -40°.

From: Adam Fikso <>
To: Pacific Bulb Society <>
Sent: Monday, February 9, 2009 2:36:18 PM
Subject: Re: [pbs] converting ºC to ºF or ºF to ºC

°  David?  Isn't  the conversion formula  supposed to be 5/9ths or 9/5ths + 
or - 32--not 40.?  That's what I remember from Berkeley High School, and U 
of C.

A little trick I learned in Hight School:
Add 40º
multiply by 5/9 or 9/5, depending upon which way you want to go
Subtract 40º

This rule is far easier to remember than any other.

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