this post was submitted on 03 Dec 2023
407 points (99.5% liked)

196

16542 readers
1962 users here now

Be sure to follow the rule before you head out.

Rule: You must post before you leave.

^other^ ^rules^

founded 1 year ago
MODERATORS
 
you are viewing a single comment's thread
view the rest of the comments
[–] LopensLeftArm 29 points 11 months ago (2 children)

The correct answer is 16. Multiplication and Division happen at the same level of priority, and are evaluated left-to-right.

[–] [email protected] 15 points 11 months ago (2 children)

No it's ambiguous, you claiming there is one right answer is actually wrong.

[–] LopensLeftArm 14 points 11 months ago (1 children)

It is not ambiguous at all, there absolutely is one right answer, and it is 16.

[–] [email protected] 8 points 11 months ago (1 children)

You're taking something you learned when you were like 9 years old and assuming it's correct in every situation forever.

Unfortunately this isn't the case and you're incorrect.

[–] LopensLeftArm 3 points 11 months ago (1 children)

Inaccurate, this has nothing to do with the mnemonic PEMDAS, this has to do with the actual order of operations it tries to instill. That order of operations is not ambiguous, there is a correct way to solve simple equations like the one above, and there is one and only one correct answer to it. That answer is 16.

[–] [email protected] 5 points 11 months ago* (last edited 11 months ago) (1 children)

And in the "actual" order of operations, if we want to pretend one exists, 2( binds more tightly than ÷

if you're going via prescriptivism, then you're wrong, because there are plenty of authoritative sources following the left hand model

if you're going via descriptivism, then you're wrong, because this thread exists

[–] LopensLeftArm 2 points 11 months ago (2 children)

No, 2( does not bind more tightly than ÷. 2( is simply 2×(..., and ÷ and × occur at the same level of priority. After resolving the addition in the parentheses, the remaining operations are resolved left to right.

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago) (1 children)

if you're going via prescriptivism, then you're wrong, because there are plenty of authoritative sources following the left hand model

if you're going via descriptivism, then you're wrong, because this thread exists

[–] LopensLeftArm 1 points 11 months ago (1 children)

No, the fact that a good many people are incorrect about how math works does not entail that math is an open question. It's not, math has actual rules to its equations and an unambiguous right answer. In this case, that answer is 16.

[–] [email protected] 3 points 11 months ago (1 children)

math has actual rules to its equations and an unambiguous right answer

you know you could've just started this by admitting you've never touched the subject at a higher level than high school and saved us all this bother

[–] LopensLeftArm 1 points 11 months ago (1 children)

I'm well familiar with math and the rules by which it works. Those who persist in arguing the case here could save the rest of us the bother by admitting they were stumped by a simple gotcha equation and are embarrassed, rather than wasting everyone's time by insisting that math is nothing but a lawless, rules-free wasteland where the answer to an equation depends on your feelings at the time.

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago) (1 children)

I’m well familiar with math and the rules by which it works

i know you won't realise this because you never got past basic calculus, but this is a very funny statement to anybody that did

they know all the "math rules" guys. which ones? ALL of them

but okay these rules: where do they come from, then?

[–] LopensLeftArm 1 points 11 months ago (1 children)

Fortunately, the rules necessary to resolve the equation in this post are extremely elementary, so none of what you're referencing has any bearing whatever.

There are exactly three things to consider in here to determine priority: parentheses, multiplication/division, and addition. The addition happens first due to the parentheses, and the remaining is evaluated left-to-right. The only correct answer here is 16.

All your deflection from your embarrassment at misreading a simple equation doesn't detract from this.

[–] [email protected] 3 points 11 months ago (1 children)

Fortunately, the rules necessary to resolve the equation in this post are extremely elementary, so none of what you’re referencing has any bearing whatever.

this would be like trying to tell a chemical engineer they didn't know what they were doing based on your understanding of the atom as a ball of protons with electrons wooshing round it like they were moons

very cute

unfortunately, if you give the expression 1 / 2x to anybody who knows what they're doing they'll interpret it as 1 / (2x) because it would be absurd not to

for reference, that's why the calculator works like this. because it's a tool designed primarily for people who actually know what they're doing with numbers, so it works how they expect it to work

[–] LopensLeftArm 1 points 11 months ago (2 children)

And there you've proven exactly what I've been saying all along. 2x works the way it does because there's a variable involved, and natural reading of that treats it as a single entity. There are no variables in the equation in the post, there are only definite numbers, parentheses, and simple mathematical operations. 8/2(2+2) is nothing more than 8/2×(2+2). There is nothing special about 2(..., this is not the equivalent of 2x.

[–] [email protected] 3 points 11 months ago (1 children)

a natural reading of 2(2+2) treats it as the same

you're straight up just spouting contradictory nonsense now because you've realised your stance doesn't make any sense, and i am very much here for it

[–] LopensLeftArm 1 points 11 months ago (2 children)

No, what I'm explaining to you is the facts behind what every calculator with any modicum of computing power will tell you, namely that 2(2+2) is identical to 2×(2+2).

[–] [email protected] 2 points 11 months ago (1 children)

ah yes it's the computing power that's at issue here

[–] LopensLeftArm 1 points 11 months ago (2 children)

Yeah, kind of. The crappier calculator is the one generating the incorrect answer. Any calculator with any real level of oomph behind it can parse this correctly to get the correct answer, 16.

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago) (1 children)

the good calculator is the one showing you adverts

~ local galaxy brain

[–] LopensLeftArm 1 points 11 months ago (1 children)

The good calculator is the one using the processing power of the phone to handle the programming necessary to correctly interpret the order of operations and arrive at the correct answer, whereas the bad calculator - despite having no ads - is a cheap piece of trash unable to contain the necessary computational logic to arrive at the correct answer.

[–] [email protected] 2 points 11 months ago (1 children)
[–] LopensLeftArm 2 points 11 months ago (1 children)

No need. The fact that you're incapable of comprehending it at this point indicates that any further attempts to explain it to you are equally likely to fall on deaf ears.

[–] [email protected] 1 points 11 months ago (1 children)
[–] LopensLeftArm 1 points 11 months ago* (last edited 11 months ago) (1 children)

And you've long since given up trying to defend your incorrect position, so I can only assume that you're childishly continuing in an attempt to get the last word. That's fine, go right ahead and have the last word, I won't reply further since it's that important to you.

[–] [email protected] 1 points 11 months ago
load more comments (1 replies)
load more comments (1 replies)
[–] [email protected] 0 points 8 months ago

2( is simply 2×(

No it isn't. 2(a+b)=(2a+2b) The Distributive Law

[–] [email protected] 1 points 8 months ago

But there actually is only 1 right answer, and unfortunately for the person you're replying to it's 1.

[–] [email protected] 6 points 11 months ago (1 children)
[–] LopensLeftArm 38 points 11 months ago (21 children)

PEMDAS should be read as Parentheses, Exponents, Multiplication and Division, Addition and Subtraction. There are four levels of priority, not six.

load more comments (21 replies)