# way way off topic

Gezeala M. Bacuño II gezeala at gmail.com
Wed Oct 24 00:52:44 UTC 2012

```% change = ( (present - past) / past ) * 100

On Tue, Oct 23, 2012 at 5:07 PM, Gary Kline <kline at thought.org> wrote:
> On Tue, Oct 23, 2012 at 08:52:49AM +0200, Polytropon wrote:
>> On Tue, 23 Oct 2012 11:31:18 +0700, Olivier Nicole wrote:
>> > Gary,
>> >
>> > On Tue, Oct 23, 2012 at 11:20 AM, Gary Kline <kline at thought.org> wrote:
>> > >
>> > > apologies up front for this math type quandary. I had it in a std C program,
>> > > but 3+ hours of grepping havent found it.  I would have bet my last cent that I
>> > > had a summary Somewhere, but cant find that either.
>> > >
>> > > here is the problem as best I can remember it.
>> > >
>> > >
>> > >         let's say that john is 8 and his older friend, jim, is 22.
>> > >         how much older is exact percentage terms is jim?
>> >
>> > That should be 22/8=2.75
>> > Jim is 275% older than John
>>
>> Jim is 175% _older_. Why? Because 100% older means 16 years,
>> as 100% refers to 8 years (8+8=16, 200% older is 8+8+8=24).
>> Percentage is always a reference to something else, in this
>> question, Jim's age in relation to John's. The word "older"
>> means "adding percentage", refering to the base value of 8,
>> "divided in 100 parts" (floating point considerations aside),
>> to finally reach the value 22.
>>
>> If the question would be different, say, "What's the percentage
>> of John's age regarding Jim's age?" In that case, it would be
>> 8/22=0.3636 being 36%. Obvious: John's age is approximately
>> 1/3 of Jim's age.
>>
>> The easiest way for creating the proper calculation is to refer
>> to the equation
>>
>>                          percentage * 100
>>       percentage value = ----------------
>>                            base value
>>
>> and resolve it to whatever is required.
>>
>> --
>> Polytropon
>> Magdeburg, Germany
>> Happy FreeBSD user since 4.0
>> Andra moi ennepe, Mousa, ...
>
>
>         yo; I THInk this is it. around line 4542 in my ~/.HowTo file::
>
>
>
> %%% find percent inc/dec [increase/decrease] between two numbers.
>
> Always figure the percentage of change relative to the original value!
> For instance: * Suppose a certain item used to sell for seventy-five
> cents a pound, you see that it's been marked up to eighty-one cents a
> pound. What is the percent increase?
>
> First, I have to find the absolute
> increase:
> Reserved 81 - 75 = 6
>
> The price has gone up six cents. Now I can find the
> percentage increase over the original price.
>
> This percentage increase is the relative change: 6/75 = 0.08
> ...or an 8% increase in price per pound.
>
>
>
>         So I was wrong about ages or speed; it's the % betwen two ints;
>         here, the inc/dec [or change] between 75 cents as compared to
>         an inflated increase of 81 cents.
>
>         1.  find abs increase:  81-75 = 6;
>         2   find the % increase over the *original* value. 6.0/75.0
>         3.  percent increase using doubles is 0.08;  so a markup of six
>             cents is an 8% rate.
>
>
>         so: going back to the ages example with john bein 8, jim, 22.
>         22-8 is 14.
>         14.0/8.0 = 1.750000
>
>         175%.  jim is 175% times older than john.  which is what you found,
>         polyt.  {I'll have to re-read your logic now that im awake..}
>
>         Or, how much more, in % is 16t than 15, it is 1.0/15.0 which is 6%.
>         etc,  etc.
>
>         Hm.  that's 0 for gary, 729 for polytrop!!
>
>         Ah, life:: accept no substitutes.
>
>
>
>
> --
>  Gary Kline  kline at thought.org  http://www.thought.org  Public Service Unix
>               Twenty-six years of service to the Unix community.
>
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