LDB415
Loc: Houston south suburb
Cool. Just ordered the book.
Delderby wrote:
My own Math shortcut converts degrees C to degrees F as follows - double the degrees C then take off 10%, and add 32. Use nearest integers!
Example: 24C x 2 = 48. less 10% (5) = 43, add 32 = 75F.
Also - 16=61 and 28=82.
Useful for the oldies like me who were brought up on Fahrenheit!
In aviation the shortcut for converting celius to Fahrenheit is Cx2+32. 15Cx2=30c+32=62F. I used 15C as this is the standard temp. in aviation for density altitude. So using your numbers 24Cx2=48C+32=80F. To convert back to celius it is the reverse: F-32/2=C; 62F-32F=30F/2=15C or 80F-32F=48F/2=24C. 59F is also used as a standard temp for density altitude so that conversion to celius is 59F-32F=27F/2=13.5C and not 15C. All this does is get you within a plus/minus of what the actual thermometer is reading
MrBob wrote:
I prev. mentioned the Trachtenberg system of mathematics using shortcuts... Here is a simple one I really like.
Multiply any 2 digit number ending in a 5 by itself... i.e. 25x25 or 75x75.
Answer will ALWAYS end in 25 and first part of answer will be the original number x the next highest number.
example. 85x85 8x9=72 and ends in 25 SO, answer is 7225...
example. 45x45 4x5=20 and ends in 25 SO, answer is 2025...
The entire Trachtenberg system is full of little shortcuts like this. Enjoy...
I prev. mentioned the Trachtenberg system of mathe... (
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And of course it works the same if you move the decimal points. 4.5x4.5=20.25 (Just remember that decimal points are slippery little things that like to move around on their own!)
--Rich
marine73 wrote:
In aviation the shortcut for converting celius to Fahrenheit is Cx2+32. 15Cx2=30c+32=62F. I used 15C as this is the standard temp. in aviation for density altitude. So using your numbers 24Cx2=48C+32=80F. To convert back to celius it is the reverse: F-32/2=C; 62F-32F=30F/2=15C or 80F-32F=48F/2=24C. 59F is also used as a standard temp for density altitude so that conversion to celius is 59F-32F=27F/2=13.5C and not 15C. All this does is get you within a plus/minus of what the actual thermometer is reading
In aviation the shortcut for converting celius to ... (
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I find this to be surprising. I have always thought that anything to do with aviation would be accurate, which of course your above shortcut isn't.
Delderby wrote:
I find this to be surprising. I have always thought that anything to do with aviation would be accurate, which of course your above shortcut isn't.
You can blame the FAA for making 15C/59F as the standard temp for a standard day. That seems to be when every thing works in harmony.
And when everything aviation related is working in harmony, that’s good and one should not ask questions. When they aren’t in harmony, planes crash and people die. As the old timers said, never look a gift horse in the mouth. Or a harmonious moment.
marine73 wrote:
You can blame the FAA for making 15C/59F as the standard temp for a standard day. That seems to be when every thing works in harmony.
Yes - my shortcut says 15C x 2 = 30, less10% (3) =27. Add 32 = 59F.
With global temperatures ranging at least between -5C and 45C in the course of a year, that would make an average of 7 "standard days" per annum - hardly a "standard" to be considered. Might as well use 16=61.
I have lived my life with a motto - "beware the experts". When I was a little lad dentists told us to brush up and down, ten years later they said do not brush up and down as this forces food particles under our gums and causes gum disease - the biggest single reason for bolstering a dentist's business. That was a bit late for me.
rlv567
Loc: Baguio City, Philippines
Delderby wrote:
Yes - my shortcut says 15C x 2 = 30, less10% (3) =27. Add 32 = 59F.
With global temperatures ranging at least between -5C and 45C in the course of a year, that would make an average of 7 "standard days" per annum - hardly a "standard" to be considered. Might as well use 16=61.
I have lived my life with a motto - "beware the experts". When I was a little lad dentists told us to brush up and down, ten years later they said do not brush up and down as this forces food particles under our gums and causes gum disease - the biggest single reason for bolstering a dentist's business. That was a bit late for me.
Yes - my shortcut says 15C x 2 = 30, less10% (3) =... (
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The conversion always has been stated as F = 9/5 C + 32.
Loren - in Beautiful Baguio City
rlv567 wrote:
The conversion always has been stated as F = 9/5 C + 32.
Loren - in Beautiful Baguio City
Yes - I prefer KISS - my brain does "double it less 10%" more easily than "times nine and divide by 5".
MrBob
Loc: lookout Mtn. NE Alabama
RiJoRi wrote:
And of course it works the same if you move the decimal points. 4.5x4.5=20.25 (Just remember that decimal points are slippery little things that like to move around on their own!)
--Rich
Too bad we did not go metric.... those little points are so easy to move...
Reuss Griffiths wrote:
-40F = -40C
Nice one - and I've just checked it out - the short cut worked.
marine73 wrote:
In aviation the shortcut for converting celius to Fahrenheit is Cx2+32. 15Cx2=30c+32=62F. I used 15C as this is the standard temp. in aviation for density altitude. So using your numbers 24Cx2=48C+32=80F. To convert back to celius it is the reverse: F-32/2=C; 62F-32F=30F/2=15C or 80F-32F=48F/2=24C. 59F is also used as a standard temp for density altitude so that conversion to celius is 59F-32F=27F/2=13.5C and not 15C. All this does is get you within a plus/minus of what the actual thermometer is reading
In aviation the shortcut for converting celius to ... (
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A shortcut that I find quite effective is. “Hey Siri, how many degrees Fahrenheit is. . . .
MrBob
Loc: lookout Mtn. NE Alabama
raymondh wrote:
A shortcut that I find quite effective is. “Hey Siri, how many degrees Fahrenheit is. . . .
But then the HIDDEN fact checkers add your question to your Dossier and WONDER why you want to know...
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