Why does 100% represent the whole of something

Question

I want to start off by saying I'm not someone who is particularly strong at math, and that this is a fairly abstract question.

Today I was reading a comment on reddit, a user posted something to the effect of if you aren't sure 100000% about doing something, you shouldn't do it. I was annoyed by the percentage they used, it's obvious that you can't have more than 100% of something. (without going over the maximum quantity)

This got me thinking. Why does 100% represent the maximum value of something?

Let's say I took a test with 10 questions and got all 10 correct. I would have received a 100% on the test. Why? Why doesn't 200% or any other number represent the maximum percent that I can achieve?

I think it might be an arbitrary value chosen. It's easy to convert numbers to percentages with 100% being the maximum.

In summary, why does 1/1 = 100%? Why doesn't 1/1 = 200%, or 137.45%?

Answer 1

Percent literally means "per hundred", as "cent" means "hundred" in French (and, originally, Latin). Hence, "percent" means "out of 100".

100% means 100 out of 100.

Answer 2

100% means $\frac{100}{100}$ (Hundred out of Hundred). In short If an apple is divided to 100 parts and you ate 5 parts, you have eaten 5% of it. you cannot eat more than 100%.

Answer 3

As already said, 100% means 100 out of 100.

To me, the only two ways to read a percentage superior to 100 is :

• An oral way of emphasizing something ("I'm 1000% sure of what I'm saying"), which is mathematically wrong.
• Talking about a rate. If a plant measures 10cm on Monday, then 20cm on Friday, it has a 100% growth rate. But if it measures, again, 10cm on Monday and then 30cm on Friday, it has a 200% growth rate. You often see this when talking/reading about economic growth.