Hey all.

I have two values I've measured one before change and one after change.

the first value is 9 and the second value is 34

Is it 9 is what percentage of 34 = Percentage Difference 9 and 34 = 116,279%

(9 - 34)/((9 + 34)/2) = 25/21.5 = 1.1627906976744 = 116.27906976744%

Percentage of increase = (9 - 34)/9 = 25/9 = 2.7777777777778 = 277.77777777778%

34 is a 227.777% increase of 9

227 seem to high.

To confirm your number, try working backwards:

278% is 2.78

9 + (9 * 2.78) = 34

9 to 18 is doubling. That's 200% (or, as you're calling it, an '100% increase')

9 to 27 is tripling. That's 300% of 9 (or a 200% 'increase')

9 to 34 is almost quadrupling. It's 378% of 9 (or a 278% 'increase')

Servant's number is correct.

I've always disliked percentages, they just complicate matters in my eyes, I prefer just the 'raw' number e.g. 2.78. A formula for increasing one value 'a' by a percentage 'x' is:

a*(100+x)/100 = b, where b is the increased number. You can rearrange this to find 'x' (your percentage)

multiply both sides by 100:

a*(100+x) = 100*b

divide both sides by 'a'

100+x = 100*b/a

subtract 100 from both sides:

x = 100*b/a-100;

Plug in your numbers (a=9, b = 34)

x = 100*34/9-100 = approx 278% same as Servant's.

Thanks all.

Its 277.78%

for some reason I get 37 back from Nanoha way.

Wow you can't complain from an increase of that amount, I wish I could do the same with me cash. I would get one of these's

for some reason I get 37 back from Nanoha way.

Would you mind posting the code you used to do that? If you use integers instead of floats then that could explain why you get such a strange value. Using my calculator I get 277.77 recurring but with code using ints I get 277 (which is expected). I'll not be getting my Aston Martin if I get 37 as my answer :P.

oh sorry when doing it on calculator i did 9 - 100 before the division. too many hours and all excited about the big gain.

Nanoha answer is correct.277.777% that is a crazy amount of extra.

It depends. As Nanoha alludes to, percentages have no intrinsic meaning or value, but they can be a useful way to present relative figures in terms of something everyone "gets". So how to present a meaningful percentage is difficult to say without context.

For example, if 9 and 34 were test scores out of a hundred (hopefully not!), then I imagine for most people natural "unit" to explain such figures in terms of is the overall maximum value of 100, and not just relative to one another. If you are talking about interest rates for a bank account, there is no such reference figure so a percentage in terms of your balance makes sense.

Does representing the information with a percentage add to your understanding? A simple ratio might be easier to understand, i.e. 2.78 or nearly 3 times higher.

Was there any intermediate data points between 9 and 34, and could there be more data points in future? If so, a graph depicting how the value is changing over time can convey lots more information than just a relative comparison of the first and last data points. For example, if the value appears to be growing exponentially then that is very different than if it looks like grew fast at first but is now reaching some upper limit.

I see ratio may be what I'm looking for 3 time better at max power setting. Both values are read when power level is at max. Both reach a max value after some time passing. Once there at max power the value stays at that constant value, 9 volts @ 0.21 amps and the modified 34 volts @ 0.46 amps.
Would I need to include the time to max power.