---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Mon 06/25/07: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 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 _____________________________________ Time: 05:41:55 AM PST US Subject: Re: Engines-List: Re: Easy - too easy From: Larry Mac Donald 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" 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 _____________________________________ Time: 09:22:03 AM PST US From: "jrc" 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. ________________________________ Message 3 _____________________________________ Time: 09:28:37 AM PST US From: "jrc" Subject: Re: Engines-List: 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" 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 _____________________________________ Time: 10:19:53 AM PST US From: "Peter Grant" Subject: RE: Engines-List: Easy - too easy 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) +++++++++++++++++++++++++++++++ 10 The Sidings, Horncastle, Lincs LN9 5UA England Tel: +44 1507 523180 Fax: +44 1507 525888 Mob: +7774 923160 ++++++++++++++++++++++++++++++++ This email may contain confidential information; if you have received it in error please delete it from your system and inform the sender. Outgoing messages are scanned by AVG 7 Professional. -----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. 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