New Math

Yang botched it by chaining = wrong.
100 − 10 = 90 + 9 = 99
❌ cringe
100 − 10 = 90
90 + 9 = 99
✔️ based

- !reactionmemes@lemmy.dbzer0.com
- I have seen this or a variation of this too many times now, saving this for my own meme responses, its too fucking useful.

Some bureaucrats in Mexico City tried this years ago.
An important ring road had two lanes in each direction. To increase its capacity, they didn't actually widen the road; they just repainted the lane markings to turn two lanes into three, and claimed a 50% capacity increase!
Everyone immediately screamed about being crammed together just centimetres apart, accidents increased and the city officials quickly u-turned; they repainted to have just 2 lanes in each direction again.
But they then tried to claim that as that was a 33% decrease, and that because they had earlier increased it 50%, that meant they had achieved a net 17% increase in the road's capacity!

TBF Yang really did write the equation in the sloppiest way possible.
Like I know what he MEANS but no math professor in the world would let this shit slide.
- Yeah if you put it:
  100 - (100 x 0,1) = 90
  90 + (90 x 0,1) = 99
  It comes quite obvious. And I know the brackets are redundant, but my coder mind forces brackets to all math formulas for readability.
  Was it on purpose, maybe.
  
  Even
  100 - 10% = 90
  90 + 10% = 99
  Works better than what he did, because that’s how you’d enter it on a standard calculator.
  
  I think of it as
  100 x 0.9 = 90
  90 x 1.1 = 99
  Am I the odd one out?
  
  Decimal commas ain't 'merican: you'd totally throw them with your weird euro math.
  
  Readability is important. I do the same thing, because just because something is technically correct doesn't mean there isn't a better way to do it. I'm very pro-bracket.
- It's twitter, why'd anyone put effort in what they write.
- That's what makes it great bait
  
  Yeah, for idiots

Don't they teach math in the US anymore? Or do you get a pass on basic subjects if you are on the football team?
- No they definitely teach math but unfortunately math is kind of useless when they don't teach critical thinking.
  Because then people blind themselves with their own bias and refuse to actually critically think about what they're reading and realize that they misread it or misunderstood it.
  
  Goddamn I'm glad I was in Gifted
  These people have no fucking clue what they missed
- Practice is important. People definitely learn this level of math, but not using it for years dulls the senses. On top of that, lots of people scrape through school doing the bare minimum. (Not always their fault of course. Not everyone has ample opportunity to excel in school due to a variety of things.) From what I hear, the bar for graduating high school is not incredibly high, so people like this don’t surprise me.
  
  Knowing basic math (and sometimes a bit more) is quite useful in life. I am currently having a beef with my bank who tried to cheat me out of a larger sum. But I know the correct methods and the correct rates, and, of course, the contract. And obviously, it really pisses them off that someone even does the calculations...
- You get a pass on pretty much every subject because the school's interested in churning out worker drones rather than thinkers. Do this long enough and you get Trump supporters.
  
  Heck, for a while, we insisted on passing kids no matter what so they weren’t “left behind”.
- They teach math from like 6th grade up as if every middle schooler in the land is going to grow up to be a sweater wearing chalkboard writing mathematician when they grow up. It's taught as a series of arbitrary rules to follow. Here's some squiggles, and now you do this to the squiggles. NO you don't do that to the squiggles, do you want to be a ditch digger you fucking waste of sperm. You do THIS to the squiggles. Can't you FUCKING tell the difference you little cuntpuke? You use the Crendicative property of intiplicity. No, it's not five, it's negative three. It's obviously negative three, What idiot would get five? I know you got five and not some other number because this is designed to be a trick question. There's only one point in this big long procedure that matters, if you decide correctly you get negative three, if you decide incorrectly you get five. And you got five.
  They do this to you for your entire adolescence.
  
  So you're bad at maths and extremely bitter about it. Ok.
  
  Yeah you're right that they act like everyone's gonna be a pure mathematician with only abstract applications. I think test standards have kinda fucked with their expectations. I'm sorry you had bad math teachers. Many of them suck at explaining the subject and act like dicks. Get enough of them in school and it's easy to lose interest in something that's extremely practical to know later in life.
- No, they don't.

Brought to you by the same people that can’t explain tides
- Tide comes in, tide goes out. You can't explain it!
  
  Bread goes in. Toast comes out. It’s a mystery!
  
  For anyone who doesn't get the reference, here you go
- Ah yes I hate those
  
  And hate windmills
- yeah they think the MOON does it lmfao, everyone knows it's the CIA's totally epic wave machine for selling more surfboards 🌊🏄‍♀️🐟

I thought this was c/funny not c/deeplyconcerning
- You want concerning....talk to teachers about gen alpha. They can't read well, their grammar sucks, they can't use PC's, they're super gullible and believe/want to purchase whatever online influencers tell them to, and just believe whatever pops up at the top of their search result or AI says.
  
  I am not convinced Alpha is unique in their gulliblity and think we should all be hesitant to believe anything we hear online about how bad 'the youths' are.

Both sides are right in a way. It just depends on what you're comparing the +/-10% to
- This is clearly about the US stock market crashing. In that case it's always the days gain/loss, in which case Yang is the only person who is right.
  This is important because a lot of people saw "down 10%" and now "up 10%" without realizing that's still day over day loss.
  
  While the idea put forward by him is correct, stating that 100-10=90+9=99 is just entirely incorrect, hence why I'm saying they're both somewhat correct
- Percent increase/decrease is change/original.
- That is the difference between percent and percentage points.

I might as well throw the same comment in here. You learn this pretty quickly when you bet on meme stocks. Down 90% then up 100% I can assure you, you are no where near where you started.
- Same with crypto. You'll get a notification something went down 10%, then up again 10%, but if you zoom out you see it's just been slowly going down on average since the last huge spike.

pegglegg back in fifth grade: 'why i need to learn this math stuff. i aint never gunna use it'
- It's not that you will regularly have a calculator in your pocket
  Checkmate
  
  you still need to know what buttons to push on the magic box, and in what order...
- That kind of math didn't start for me until letters started showing up in it. This is basic shit though!

Not even close to that anyway, the dow jones for example went from 44k to 37k back up to 40k. Still hasn't even regained half the value it lost.

Yeah he totally cooked Yang. That guy has NO IDEA where the 9 came from.

It's only the same if it's up 10% compared to the original number. It all depends on your time period, you could be up 30% compared to 7 years ago.
- Tesla stock prices are good example of this. They are down ~50% since december and up ~70% since lowest point in april last year.

This is why in forecasting and time series analysis is used the log difference, a 10% increase or decrease on the log scale gives you the same value being added or removed.
- Yes, that requires a reference value to be decided upon beforehand.
  
  Not really, you do t=n and t=n+1, for n= 1, 2, 3 for a quick view on volatility.
  Then ypu look up for correlations between e[t=n | t= 0, t= 1...] for different Ns. For more I would need to check out my notes

Multiplication is commutative dipshits.
A x B = B x A
So 1.1 x .9 is always going to be .99, regardless of the order. Didn’t we learn this in like middle school?
(Edit … to be clear I’m calling the people in the image dipshits, not the people commenting here).
- Huh? We're talking about percentages not multiplication. Where'd the 1.1 and .9 come from?
  
  If you increase something by 10% you’re doing this:
  (10% • X) + X
  (.1 • X) + X
  1.1 • X
  So you’re just multiplying the original value by 1.1. Similarly for subtracting 10% you’re multiplying by .9
  So the order in which you add or subtract 10% doesn’t matter. You always get the same number.
- who said the order matters?

Bunch of methamagicians up in here

I wonder why he has a peg leg

What's it called when you "tether" a certain value at 100%. Often for economic graphs. In that case the second guy could be correct and if that's all they know it would make sense

Just noticed if you also decrease something by 10%, then increase by 10%, you also get a net loss of 1. Math itself is biased towards loss.
Anyone convinced in the malevolent creator theory yet?
- Math isn't biased. Flawed reasoning is. For x ≠ 0
  (1 + x)(1 − x) = 1 − x² < 1
  The correct way to cancel scaling by a proportion is its reciprocal, ie, for x ≠ 0
  x ∙ ¹⁄ₓ = 1
  A 10% decrease is ⁹⁄₁₀
  100% − 10% = 90% = ⁹⁄₁₀
  Its reciprocal is ¹⁰⁄₉, a ¹⁄₉ = 11¹⁄₉% increase
  1 / (100% − 10%) = ¹⁰⁄₉ = 100% + 11¹⁄₉%
  We make it complicated by stating increase/decrease & percent instead of simple scaling factors. The western world has a weird 💯 fetish almost as funny as ancient mesopotamians and the number 60.
  In general, for proportional change x, the proportional change y to cancel it is the solution of
  (1 + x)(1 + y) = 1
  y = (1 + x)⁻¹ − 1
- Increase by 10 then decrease by 10. Same problem. Math is lossy.
  
  Adding flat numbers is different from adding a percent.

Why did this have to be the UBI guy?
Was Yang controlled opposition or just dumb as shit?
- What are you talking about? Yang is the one who is right here.
  
  They're just upset they have to agree with someone they don't like.
  
  TLDR - The use of notation is poor - I'd call it sloppy. His post would be much better (to me) without the example.
  Most alarmingly he's written an inequality as an equality, and he's not really explaining the units / percentages at all. I think this type of thing is really unhelpful to people who struggle with maths and maths notation. It seems evident that the last reply's author does struggle and the example is part of their confusion, it certainly didn't help.
  It makes me think he doesn't give a shit what he writes or about the audience. That makes me inclined to give no shits about it too. Either way this style of communication is all red flags to me - I guess thats why I avoid all this twittery in general.
  Anyway, I guess I care enough to type a few more shits . . . I'm sure i've already put in way more thought than the OOP . . . I think he should have written something that spells out a bit more what is going on , and used an inequality, like:
  100 - 100 x (10/100) != 90 + 90 x (10/100)
  100 - 100 x (10/100) > 90 + 90 x (10/100)
  Or:
  100 - 100 x (10/100) = 90
  90 + 90 x (10/100) = 99
  As others have pointed out, in some contexts (like price indices) people convert time series data into indexes where 1 unit is referenced to: 100*1/(nominal reference price)
  So for units defined as "percent of reference price", we d can use the simple expressions:
  100 - 10 =90
  90 + 10=100 (edited my own slop)
  Some people might, also sloppily, refer to the 10 as a "percent change" as shorthand for the units. It is a percentage, but one should be clear percent of what.
  If the context is more specifically weighted price indices then it can get more complex, but commentators may simply by saying "up by 10%", when it's really a more complex index value movement where the weightings can change. This all makes financial data in particular very confusing to those who struggle with maths, which is bad and it'd be nice if these things were communicated in a way that makes it as easy as possible for them.
- 10 percent of 90 is 9.
  90 + 9 = 99
- I mean, he was right about what AI was about to do. Expecting everyone to be able to live on $1000/month and not taking about the huge concentrations of wealth and power was the idiotic part.