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I saw this definition online from the Free Dictionary regarding the definition of percent (%):

"Noun 1. a percent sign - a sign (`%') used to indicate that the number preceding it should be understood as a proportion multiplied by 100."

What is this "proportion" multiplied by 100?

When I think of a proportion, I think of a/b = c/d. How can a number preceding the percent sign be understood as a proportion  X 100?

I thank you for your reply!

ANSWER: Every proportion can be written with denominator equal to 100.
Percentage means the amount or number out of 100
or per 100. It is the numerator when the denominator is 100

So , for example, 2/5 = 40/100 = 40%
The definition given by the dictionary is ok, it just says to find the percentage which is equal to the proportion or fraction , you just multiply 100 by the fraction .
So the percentage given by 2/5 is (2/5) (100) = 40

---------- FOLLOW-UP ----------


I want to thank you for your reply.

In this Free Dictionary definition, does the word "proportion" indicate a fraction? In your example, you used 2/5.  Is this the proportion that is multiplied by 100?

Proportion is confusing in this definition because I think of two fractions not one separated by an equal sign: 1/2 = 2/4.

Something like (2/5 = 40/100) X 100 is not what the definition is indicating is it?

I thank you for your follow-up reply.

Proportion , ratio and fraction all are the same thing.

a/b is a proportion

a/b = c/d  is an equation that shows that two proportions are the same .

4/12 = 2/6 = 1/3  are three proportions that are equal

Yes , it's confusing to have three different words for the same thing .  

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