Mathematicians! How do I calculate percent difference?

[her209]

3.06 / 1.86 = 1.64 = 64% faster.

This is how I calculate
It as well. It's the reduced formula for:

(B-A)/A = B/A - A/A = B/A - 1

 

[JTsyo]

Thank you very much. It was so easy! I had no idea. Even someone so horrible in math like me wouldn't have any trouble using this simple formula.

Now if someone could explain to me WHY this formula works the way it works? Why do we have to divide by the lesser number after subtracting it from the bigger number?

It's not a matter of bigger or smaller, it's a question of which one is your reference. If the 1.86 was the reference, you would divide by that if not then by 3.06.

Same with with the race times. Are you looking for how much faster you are or how much slower he is.

 

[rcpratt]

Protip: look for "than." The number following "than" is your reference.

 

[moonbogg]

Percentage cross multiplication thingies.

 

[pete6032]

OP how do you leave a tip when you go out to a restaurant?

 

[ringtail]

Not sure how to properly google for this... What is the phrase I should type into google?


Lets say I got 2 identical CPUs... One runs at 1.86GHZ and the other at 3.06GHz... How much percent is one faster/slower than the other?

or...


I ran a mile in 40min while my friend ran it in 50min... How many percent was I faster?


Stuff like that....http://patagonia.typepad.com/.a/6a00d8341d07fd53ef01287783b4ee970c-500wi


How do people calculate these things?

% change that the new value is compared to the original value =
new value - original value DIVIDED BY original value

% change that the old original value was compared to the new value =
original value - new value DIVIDED BY new value

Rincon in the foreground, looking up the Santa Barbara coast

 

[dullard]

Difference divided by actual, times 100.

I am ashamed of you DrPizza.

You never EVER multiply times 100 with percentages. You could multiply by 100%, but never by 100.

Multiplying by 1 is okay. 1 = 100%. Multiplying by 100 is just plain wrong.

If I make $20,000 per year and you make $40,000, then you make ($40,000 - $20,000) / ($20,000) = 20000 / 20000 = 1 = 100% more than what I make. You do not make 20000 / 20000 * 100 = 100 = 10000% more than what I make!

 

[Ruptga]

When doing this sort of mental math I do it by fractions, then convert to percents. Look at it this way, 5/8 of 1 is 5/8 (duh), and 1 is five eighths (5/8) of eight fifths (8/5). The fraction gets flipped end over end is all.

 

[shortylickens]

This is why they keep sending jobs to India.

 

[Babbles]

Relative Percent Difference (RPD) is calculated as the absolute value difference divided by the average of the two. Then convert to percent as needed. In Excel I believe it is:

=abs(A:B)/avg(a:b)

For what it's worth I've been an analytical scientist for ~15 years and this is how we do RPD in the lab. Again, this is the percent difference between two values, not the increase/decrease between them.

EDIT:
I was quick to post, but didn't realize the OP was also looking for a percent increase and not just a percent difference.

 

[Fenixgoon]

(3.06/1.86)-1 = 64.5%

I went to grade school in Central America and they taught us how to work with percentages. Schools in the US must really suck.

actually, 3.06/1.86 - 1 = 0.645

which, x100 (pct)...gives you 64.5%.

just sayin'

 

[Babbles]

Thank you very much. It was so easy! I had no idea. Even someone so horrible in math like me wouldn't have any trouble using this simple formula.

Now if someone could explain to me WHY this formula works the way it works? Why do we have to divide by the lesser number after subtracting it from the bigger number?

I think somebody else mentioned it, but it is not necessarily dividing by the smaller or larger number, but rather your point of reference. It can be an increase or decrease depending on the value change, but the point is if the frame of reference is relative to the first value then you divide by that first value.

 

[jagec]

You have no idea how bad US schools are......im 20 and have never seen this formula before.

I don't care how bad your school was...you have the internet. If you don't know how to do simple math, it's because you don't WANT to know. The information is out there.

 

[Ruptga]

I don't care how bad your school was...you have the internet. If you don't know how to do simple math, it's because you don't WANT to know. The information is out there.

You say that like it's a bad thing. A lot of people have no idea what they don't know, including many that would like to know if only they knew that they don't know.

 

[John Connor]

What is the percentage of -40 from 100?

 

[Ruptga]

What is the percentage of -40 from 100?

Is this one of those jokes that only makes sense immediately after a severe brain injury?

 

[dave_the_nerd]

I forgot when I learned how to do this. But I know.

 

[DCal430]

Percent increase and difference are two different things. Which one do you actually need.

 

[John Connor]

http://www.percentagecalculator.net/

This fucker doesn't work!

 

[Smoblikat]

OP how do you leave a tip when you go out to a restaurant?

Take 10%, double it. Round up for good service, less if anything but good service.

 

[Braznor]

Jesus H Christ!

 

[John Connor]

What?

 

[yhelothar]

It should be purely intuitive how to do percentages once you understand its meaning. Percentages show you the proportion an amount is relative to a given amount, and scaled to 100. 1.5 fits into 0.5, 3 times, scale that to 100 and you get 300%. 1.5 is 300% of 0.5. So here you were trying to see how many times 0.5 fits into 1.5, so that's a simple division problem, 1.5/0.5. How much bigger is 1.5 compared to 0.5? Well, it's bigger by 1, so 1 is 2x bigger(0.5/1) than 0.5, or 200% bigger.
How much smaller is 0.5 compared to 1.5? It's smaller by 1, and since you're comparing it to 1.5 now, 1 is 2/3rd the size of 1.5, so it's 66.7% smaller.

 

[yhelothar]

What is the percentage of -40 from 100?

-140%

 

[Brian Stirling]

Let's say you make $1000/wk and your company tells you they are having a difficult period and will be reducing everyone's pay by 25% but will give it back in 3 months. 3 months later they tell you they're giving it back and will increase everyone's pay by the same 25%.

Question, are you back to earning $1000/wk?


Brian