Did this turn into an /iamverysmart thread ?
this post was submitted on 01 Dec 2024
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I've always wondered how to disambiguate multiplication and addition of percentages. I guess that's what percentage points are for?
10% of your people vote for a party.
The votes increase by 10% => now 11%
The votes increase by 200% => now 30%
The votes increased by 50 percent points => now 60%
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Convert percentage to fraction, i.e, 80% become 0.8 Then multiply with initial value
If it says 80% more use initial + (initial*80) or simply initial*1.8
Or if it says 80% less, use - in above calculation or multiply by 0.2
I find percentages more neat when used as fractional number Edited to escape the multiplication symbol
It's really not even converting, as percent is literally "1/100" (per-cent = per 100). It's purely convenient shorthand.
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It's really pretty simple - if something increases by 80%, you add 80% of whatever it already is... one dollar becomes $1.80... one percent becomes 1.8 percent.
Most people don't understand it because they've seen it done wrong so often, the wrong way seems right.
I'm quite willing to bet that 70% of the population has no clue that percentages, fractions, and decimals are the same thing.
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I think it's ambiguous and the 90% actually makes more sense. If you increase something by 5m you are taking the original value and adding 5m to it. For multiplication you should probably avoid the word increase and say scaled by instead. 10% scaled by 180% is 18%.
The different ways in which numbers slide up, down, sideways, diagonally.
Is the example in the post part of the fifth type of arithmetic?
- Addition +
- Subtraction -
- Multiplication x
- Division /
- Modulo %
The first time I learned about modulo as its' own branch of arithmetic was long out of school already, I had only hazily heard of it, on a PBS Nova documentary in the 1990s about Fermat's famous theorem and when it was proven after centuries of failed tries.
No it's not modulo, it's how to talk about increasing a number by a percentage of the number.
Yeah we just learned "by" was a standard term for multiplication. So increased by 80% was just 1.8 times whatever you started with. "Divide by" meaning multiply inversely
Language translating to artithmetic. I'm sure it doesn't always line up, as we change language quite often.
Dark Souls cleared this up for me real quick.
well it's ambiguous. Its also a sloppy way of expressing an increase by 80 percentage points.
That's not sloppy, that's simply wrong
Fair enough, I'm inclined to agree. It's a relatively common error though, still leaving it ambiguous outside of circles where you expect people to express themselves with mathematical precision.
So you're telling me there's a chance?
I play video games; I need to know if the percentage is additive or multiplicative.
"+100%" looks pretty good until you see what "×25%" actually gives you.
×25% gives you 1/4 the original value, whereas +100% is double the original value, let's say 8/4 to keep it consistent. ×125% (in case a 1 is missing) is still only 5/4 the original value.
Is there a typo in your comment?
I feel they might've left something out. If you're at base value still an additive 100% increase (1+1=2) is better than a multiplicative 25% (1×1.25=1.25) increase but in games where bonuses stack another additive 100% increase would raise the effective value by 50% instead (1+1+1=3) whereas another multiplicative 25% would still raise the total by that much (1×1.25×1.25=1.56) so if you're stacking a lot of bonuses, eventually the multplicative ones are more effective. As for how many steps it would take to be equal in our example... 1+1×X=1×1.25^X I'm not gonna do this in my bed on my phone but that equation should already tell you that the right side grows faster when X -> infinity
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In video games they commonly use that to mean they are multiplying by 25. We know it's not correct in stats. This is why game wikis commonly put the actual formula for things rather than the tooltip the developers wrote.
Games use x25% or x25? Technically the first divides the score by 4.
We are aware of what it actually does mathematically. Please re-read what I wrote.
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Biggest lie in a game's tooltip/description of an item was how the formula for Armor Piercing rounds in Fallout 1 and 2 was bad, so instead of being stronger than regular rounds, they were weaker.
That's not even a stat question, it is a english question. It is an increase by 80% not to 80%
Statistics only come to play to figure out our new chances.
Maybe I'm wrong but by writing "increase by 80%" there is ambiguity you don't get if you instead spelled out:
- Increase by 80 percent
- Increase by 80 percentage points
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Or "by 80 percentage points"
"By 80 percentage points" means add 80 more points to a number of percentage points, so 5% becomes 85%. "By 80 percent" means add 80 percent of the current value.
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That's why when presenting numbers at work, we always distinguish a movement of X % (percent) from a movement of X ppts (percentage points)