Aversion to Conversion

The look on the face of an American when told of a weight in kilograms or an Indian when told the temperature in Farenheit, is priceless. What ….wait ….how ….WHAT?

I refer to Unit Converter for any queries, but in the age of smart phones and tablets, unit conversion a piece of cake. Problem arises when you don’t have technology on hand.

I’ll be discussing some often used conversion, which scare a lot of people. These are simplified and can be used in conversation, but keep in mind that though these not exactly accurate, they can pass of as one and in the process, make you look like a genius 😀

First trick, change the actual number to the nearest even number. Keep this in mind, always round up the decimals too.

Next is to know what is the actual conversion factor.

Last is to simplify the conversion factor into something manageable.

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LENGTH

mile to kilo-metre (note: metre is British, meter is American)
1 mile = 1.6 Km => so conversion factor is 1.6
add half of the original to the original #, plus one-tenth of original
eg:
10 mile -> 5 + 10, + 1 -> 16 Km   [Actual: 16.08 Km]
147 mile -> ~150 mile -> 75 + 150, + 15 -> 240 [Actual: 236.6 Km]

kilo-metre to mile
half of original #, plus one-tenth of original #
eg:
10 Km -> 5, +1 -> 6 miles   [Actual: 6.2 miles]
133 Km -> ~134 Km -> 67, + 13 -> 80 miles   [Actual: 82.6 miles]

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MASS

pounds to kilo-grams
2.2 lbs = 1 kg => conversion factor is 2.2
half, minus (half of one-tenths)
eg:
100 lbs -> 50, – (half of 10) -> 50 – 5 -> 45 Kg   [Actual: 45.4 Kg]
227 lbs -> ~230 lbs -> 115, – (half of 23) -> 115 – 11.5 -> 103 Kg  [Actual: 103 Kg]

kilo-grams to pounds
double, plus (2x one-tenth)
eg:
100 Kg -> 200, + (2×10) -> 220 lbs   [Actual: 220.5 lbs]
59 Kg -> ~60 Kg -> 120, + (2×6) -> 132 lbs [Actual: 130 lbs]

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TEMPERATURE

This is a bit complex, but hold on it’s easy.
The relationship between Centigrade (or Celsius) and Farenheit, the 2 most used units of temperature is:
C/5 = (F-32)/9

The key here is the 9 and 5. If you take 5 from the left hand side of the eqution to the right, 5/9 becomes 5/10 -> 1/2 or half.

Take 9 to the other side, 9/5 -> 10/5 or 2.

And life becomes so much easier.

Since we are taking the liberty of equating 5/9 as half (or 9/5 as 2), we have to compensate at some point. That comes at the end. Follow the examples and you should get it.

-10 deg C = (-10×2) + 32 = 12 deg F   [Actual: 14 deg F] {+2}
1 deg C = (1×2) + 32 = 34 deg F     [Actual: 33.8 deg F] {-0.2}
10 deg C = (10×2) + 32 = 52 deg F   [Actual: 50 deg F] {-2}
20 deg C = (20×2) + 32 = 72 deg F   [Actual: 68 deg F] {-4}
30 deg C = (30×2) + 32 = 92 deg F   [Actual: 86 deg F] {-6}

My advice, when converting from Centigrade to Farenheit, double the original and just add 30 at the end, instead of 32, if the original number is a positive number, or add 32 if the original numer is negative.

-10 deg F = (-10 – 32)/2 = -21 deg C   [Actual: -23.33 deg C] {-2.33}
1 deg F = (1 – 32)/2 = -15 deg C     [Actual: -17.22 deg C] {-2.22}
10 deg F = (10 – 32)/2 = -11 deg C   [Actual: -12.22 deg C] {-1.22}
40 deg F = (40 – 32)/2 = 4 deg C     [Actual: 4.44 deg C] {+0.44}
80 deg F = (80 – 32)/2 = 24 deg C    [Actual: 26.67 deg C] {+2.67}

So, when converting from Farenheit to Centigrade, subtract 32 from the original, and half.
Add 1 or 2 if the original number was 32 or greater, subtract 1 or 2, if the original number was 31 or less.


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FUEL CONSUMPTION

Here we are converting kilometer/liter (km/l or kmpl) to miles/gallon[US] (mpg) and vice-versa.

I won’t go into details of these, here is the simple conversion.

km/l to mpg -> Add 2 and double

example1: 10 km/l is actually 23.5 mpg. By my method, you will arrive at 24 mpg.
example2: 25 km/l (the Tata Nano!) is actually 58.8 mpg. By my method, you will arrive at 54 mpg. Not perfect but gets you close enough

mpg to km/l -> Half and subtract 2

example1: 30 mpg is actually 12.8 km/l. By my method, you will arrive at 13 km/l
example2: 44 mpg (Toyota Prius) is actually 18.7 km/l. By my method, you will arrive at 20 km/l.

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Categories: Demystify | 1 Comment

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One thought on “Aversion to Conversion

  1. Neha Arya

    I do the same thing. This is a very informative article. I hope many read this to avoid confusion.

    Two thumbs up!!

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