Dont even know where to begin to solve this one.

D

DreadfulCadillac

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I don't know what sub forum to post this in, i'm horrible at math..
I need to know the percent difference between 13.51 and 13.46 and don't know how..
I've tried looking online, and in other places but I can't figure it out.

What i need help with is the difference between 13.51 and 13.46, but in percent form..
I hope you guys can help, im new here. Thanks in advance!
 
Try to use "I need to improve in this area" instead of "I'm horrible at X".
In order to find the percent form difference you need to know which number represents the 100%. It's usually clear, e.g. discount percentage is based on the original price (original price is 100%).
In your example it's not clear. Let's say it's 13.51.
There are several ways to proceed, here's one:
What's the difference between the numbers? Let's call it d, but you'll calculate it.
Now we have:
13.51 is 100%
d is x%.
This is a proportion problem. Use your favorite method to find x. E.g. 13.51/100 = d/x, x = d*100/13.51
 
As lev mentioned, a percentage always has a "base." A percentage is a measure relative to some number, the base.

The difference between 50 and 40 is 10 or - 10 depending on the base. So the percentage change is either
+10 divided by 40 = plus 25% if 40 is the base or -10 divided by 50 = minus 20% if 50 is the base. This can confuse people. Sales in 2017 were 25% higher than in 2018 means EXACTLY the same thing as sales in 2018 were 20% lower than in 2017. The percentage changes when the base changes even though the numeric facts are the same.

Now as lev also mentioned, in certain contexts there is a common understanding of what the base is. So for example in economic statistics, frequently the number for the earliest year for which a reliable number is available is the base. But if you want to avoid confusing or misleading people, specify what the base is. And if are given a percentage without also being given at least some clue as to what the base is, someone may be trying to mislead you.

The formulas themselves are arithmetically simple.

percentage = 100 times the other number divided by the base number

percentage change = the percentage minus 100.

Any confusion you may have is not because you are terrible at math but because whoever taught you was a terrible teacher. I am willing to bet no one has talked to you about the importance of specifying a base or about how percentages shift when you change the base.

So if 13.51 is the base, the percentage is

[MATH]100 * \dfrac{13.46}{13.51} \approx 99.63\%[/MATH]
and the percentage change is

[MATH]\approx 99.63\% - 100\% = -0.37\%.[/MATH]
If 13.46 is the base the percentage is

[MATH]100 * \dfrac{13.51}{13.46} \approx 100.37\%.[/MATH]
And the percentage change is

[MATH]100.37\% - 100\% = +0.37\%.[/MATH]
 
Last edited:
Woah..thanks guys for all your help! I learned a lot! I was getting very confused before with the percentage before because of the decimals in it, lol. I figured out that 13.46 is the base, and that a base is a thing that exists in math.
Cause in this scenario (it's actually something in a video game) i'm giving 13.46 goods for one currency , so it is the most expensive ratio then 13.51 goods for one currency, so the savings for customers if they choose the buk package with the rat of 13.51 is .37%?

(Don't worry, i'm not buying anything ingame, its part of the game economy where people buy goods from other ingame player that they dont have using a easily available currency)
I guess If I want to become a Congressman as a adult which I do, I will really have to understand math more.
Also, Its cool to know that when you know the right formula, the math is not to difficult. I suppose I shouldn't hate math so much as it can be used to solve stuff, make money, and can be applied in real life.. Its just HARD sometimes. lol
So again I know im typing way to much here, but THANK YOU SO MUCH!
 
Last edited:
JeffM said:
As lev mentioned, a percentage always has a "base." A percentage is a measure relative to some number, the base.

The difference between 50 and 40 is 10 or - 10 depending on the base. So the percentage change is either
+10 divided by 40 = plus 25% if 40 is the base or -10 divided by 50 = minus 20% if 50 is the base. This can confuse people. Sales in 2017 were 25% higher than in 2018 means EXACTLY the same thing as sales in 2018 were 20% lower than in 2017. The percentage changes when the base changes even though the numeric facts are the same.

Now as lev also mentioned, in certain contexts there is a common understanding of what the base is. So for example in economic statistics, frequently the number for the earliest year for which a reliable number is available is the base. But if you want to avoid confusing or misleading people, specify what the base is. And if are given a percentage without also being given at least some clue as to what the base is, someone may be trying to mislead you.

The formulas themselves are arithmetically simple.

percentage = 100 times the other number divided by the base number

percentage change = the percentage minus 100.

Any confusion you may have is not because you are terrible at math but because whoever taught you was a terrible teacher. I am willing to bet no one has talked to you about the importance of specifying a base or about how percentages shift when you change the base.

So if 13.51 is the base, the percentage is

[MATH]100 * \dfrac{13.46}{13.51} \approx 99.63\%[/MATH]
and the percentage change is

[MATH]\approx 99.63\% - 100\% = -0.37\%.[/MATH]
If 13.46 is the base the percentage is

[MATH]100 * \dfrac{13.51}{13.46} \approx 100.37\%.[/MATH]
And the percentage change is

[MATH]100.37\% - 100\% = +0.37\%.[/MATH]
Click to expand...
Just to make sure I understand this, this means that if..
I had 15.76 and 13.99 (2 random numbers) and 13.99 is the base number, I would go like this to figure out the difference between them?
100 * 15.76/13.99 = 112.6% then go 112.6%-100 to get 12.6%,the difference between both numbers?

I tried writing the fraction symbol like you did, but couldn't do it so i had to write it sideways.
 
DreadfulCadillac said:
Just to make sure I understand this, this means that if..
I had 15.76 and 13.99 (2 random numbers) and 13.99 is the base number, I would go like this to figure out the difference between them?
100 * 15.76/13.99 = 112.6% then go 112.6%-100 to get 12.6%,the difference between both numbers?

I tried writing the fraction symbol like you did, but couldn't do it so i had to write it sideways.
Click to expand...
You have the idea perfectly. Quite simple once someone bothers to explain about a base.

A minor computational point. You never have to bother with calculating 100 * base / base. That will always equal 100. So to get the change from the base in percentage terms just subtract 100 from the percentage itself. The result will be that an increase will give you a positive number whereas a decrease will give you a negative number, provided the base itself is a positive number.

You cannot compute percentages from a base of zero, and I strongly recommend never calculating percentages from a negative base.
 
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