Today's Message Index:
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1. 05:41 AM - Re: Re: Easy - too easy (Larry Mac Donald)
2. 09:22 AM - Re: Easy - too easy (jrc)
3. 09:28 AM - Re: Easy - too easy (jrc)
4. 10:19 AM - Re: Easy - too easy (Peter Grant)
Message 1
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| Subject: | Re: Easy - too easy |
Thanks Ferg,
That's an annoying little piece of arithmetic. When it's
not critical, and when I can accept an answer within
2 or 3 degrees I use something I learned from a friend
in Toronto. I simply take F. subtract 30 and divide by 2 to get C.
Or take C. double it and add 30. Works a lot of the time for me.
On Sun, 24 Jun 2007 08:18:26 -0700 "Fergus Kyle" <VE3LVO@rac.ca> writes:
>
> Right, Larry,
> Basically, the topic was an easy way to convert. However
> you can see the arithmatic fialed and although the answer was
> correct, the math wasn't. I was just noting that the easier the
> arithmatic, the greater the need to do it twice.....
> Cheers, Ferg
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=120344#120344
>
>
>
>
>
>
>
>
>
>
>
>
Message 2
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| Subject: | Re: Easy - too easy |
Lets try that, using 100C (the boiling point of water).
2*100+30=230F
The correct answer is 212F
The error is 28F.
Is that close enough? (it's slightly more than 1-2 degrees)
The exact answer requires only one more substraction.
JimC
----- Original Message -----
> Rule of thumb is easiest. Double it and add 30. Normally accurate within
> 1-2 degrees. Opposite for converting back.
Message 3
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| Subject: | Re: Easy - too easy |
The brackets are optional, not required.
2X-(2X/10) is the same as 2(X-X/10) is the same as 2X-2X/10 is the same as
2X(1-0.1) is the same as 1.8X
Personally, I think its easiest to just do the thing in your head. :-)
JimC
----- Original Message -----
From: "Dave Nellis" <truflite@yahoo.com>
Sent: Sunday, June 24, 2007 8:30 PM
Subject: Re: Engines-List: Easy - too easy
>
> Should read 2X-(2X/10)+ 32=F. Math in brackets is
> done first. Hey, I do remember something from high
> school. :D
>
> Dave
Message 4
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Let's try the UK version:
C to F = double it, less 10%, add 32
Eg 100C x 2 = 200 - 10% = 180 + 32 = 212F
That's pretty close for me!
F to C slightly less accurate
F less 32, add 10%, halve it
Eg 212 - 32 = 180, add 10% = 198, halve it = 99C
Still good enough for me!
Kind regards
Peter Grant - UK Sportcruiser #4 (waiting)
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-----Original Message-----
From: owner-engines-list-server@matronics.com
[mailto:owner-engines-list-server@matronics.com] On Behalf Of jrc
Sent: 25 June 2007 17:20
Subject: Re: Engines-List: Easy - too easy
Lets try that, using 100C (the boiling point of water).
2*100+30=230F
The correct answer is 212F
The error is 28F.
Is that close enough? (it's slightly more than 1-2 degrees)
The exact answer requires only one more substraction.
JimC
----- Original Message -----
> Rule of thumb is easiest. Double it and add 30. Normally accurate within
> 1-2 degrees. Opposite for converting back.
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