watches the people with basic math skills fight to the death over the answer
this post was submitted on 03 Dec 2023
203 points (100.0% liked)
196
667 readers
33 users here now
Be sure to follow the rule before you head out.
Rule: You must post before you leave.
founded 1 year ago
MODERATORS
Please Excuse My Dear Aunt Sally, she downloaded a shitty ad-infested calculator from the Google Play store.
Unfortunately, it's the best calculator I could find so far (for my own needs). I paid to remove the ads though, ads bother me way too much to use something infested with them.
If you're willing to pirate (or legally generate) a TI calculator ROM, then Graph 89 is probably what you're looking for. This is what I use as my daily driver calculator with a TI-89 ROM.
load more comments
(1 replies)
wabbitemu!!! Its literally a ti emulator
[...] the question is ambiguous. There is no right or wrong if there are different conflicting rules. The only ones who claim that there is one rule are the ones which are wrong!
https://people.math.harvard.edu/~knill/pedagogy/ambiguity/index.html
As youngsters, math students are drilled in a particular
convention for the "order of operations," which dictates the order thus:
parentheses, exponents, multiplication and division (to be treated
on equal footing, with ties broken by working from left to right), and
addition and subtraction (likewise of equal priority, with ties similarly
broken). Strict adherence to this elementary PEMDAS convention, I argued,
leads to only one answer: 16.Nonetheless, many readers (including my editor), equally adherent to what
they regarded as the standard order of operations, strenuously insisted
the right answer was 1. What was going on? After reading through the
many comments on the article, I realized most of these respondents were
using a different (and more sophisticated) convention than the elementary
PEMDAS convention I had described in the article.In this more sophisticated convention, which is often used in
algebra, implicit multiplication is given higher priority than explicit
multiplication or explicit division, in which those operations are written
explicitly with symbols like x * / or ÷. Under this more sophisticated
convention, the implicit multiplication in 2(2 + 2) is given higher
priority than the explicit division in 8÷2(2 + 2). In other words,
2(2+2) should be evaluated first. Doing so yields 8÷2(2 + 2) = 8÷8 = 1.
By the same rule, many commenters argued that the expression 8 ÷ 2(4)
was not synonymous with 8÷2x4, because the parentheses demanded immediate
resolution, thus giving 8÷8 = 1 again.This convention is very reasonable, and I agree that the answer is 1
if we adhere to it. But it is not universally adopted.
Exactly, explicit multiplication is part of the parenthesis so it comes first in order of operations
load more comments
(3 replies)
I'm with the right answer here. / and * have same precedence and if you wanted to treat 2(2+2) as a single unit, you should have written it like (2*(2+2)).
It's pretty common even in academic literature to treat implied multiplication as having higher precedence than explicit multiplication/division. Otherwise an expression like 1 / 2n would have to be interpreted as (1 / 2) * n rather than the more natural 1 / (2 * n).
A lot of this bullshit can be avoided with better notation systems, but calculators tend to be limited in what you can write, so meh. Unless you want to mislead people for the memes, just put parentheses around things.
That's fair. Personally, I just have a grudge against math notation in general. Makes my programmer brain hurt when there's no consistency and a lot of implicit rules.
Then again, I also like Lisp so I'm not exactly without sin.
load more comments
(1 replies)
load more comments
(1 replies)
load more comments
(1 replies)
Left is correct; implicit multiplication takes precedence over explicit multiplication or division.
What the fuck is the difference in implicit vs explicit? It’s the same operation, why the fuck does it matter if there is a symbol?
Multiplication comes first, then division.
Division is a form of Multiplication, just as subtraction is a form of addition. You multiply and divide in the same step, left to right
No, multiplication and division are resolved from left to right in the same step. But implicit multiplication (xy, as opposed to x*y) happens first.
load more comments
(1 replies)
load more comments
(3 replies)
this comment section illustrates perfectly why i hate maths so much lmao
love ambiguous, confusing rules nobody can even agree on!
The problem isn't math, it's the people that suck at at it who write ambigous terms like this, and all the people in the comments who weren't educated properly on what conventions are.
Yeah, you could easily make this more straightforward by putting parentheses around 8÷2. It's like saying literature sucks because Finnegans Wake is incomprehensible.
load more comments
(1 replies)
Huge shout out to the jaded AF high school math teachers that don't give a fuck any more!
load more comments
(1 replies)
load more comments
(1 replies)
PEMDAS
Parenthesis, exponents, multiplication, division, addition, subtraction.
The rule is much older than me and they taught it in school. Nothing ambiguous about it, homie. The phone app is fucked up. Calculator nailed it.
The comment from subignition explains that the phone's answer, 16, is what you get by strictly following PEMDAS: the rule is that multiplication and division have the same precedence, and you evaluate them from left-to-right.
The calculator uses a different convention where either multiplication has higher priority than division, or where "implicit" multiplication has higher priority (where there is no multiply sign between adjacent expressions).
But explicit multiplication is part of the parenthesis, so still comes before division or exponent
The parentheses step only covers expressions inside parentheses. That's 2 + 2 in this case. The times-2 part is outside the parentheses so it's evaluated in a different step.
load more comments
(1 replies)
load more comments
(1 replies)
i know about pemdas and also my brother in christ half the people in the comments are saying the phone app is right lmao
edit: my first answer was 16
load more comments
(1 replies)
The problem is that there's no "external" parentheses to really tell us which is right: (8 / 2) * 4 or 8 / (2 * 4)
The amount of comments here shows how much debate this "simple" thing generates
load more comments
(1 replies)
16
People in this thread need to watch this: https://youtu.be/lLCDca6dYpA
And the much longer video by the same person:
Problem with PEMDAS: Why Calculators Disagree https://youtu.be/4x-BcYCiKCk
load more comments
(1 replies)
load more comments
(6 replies)
For anyone like me who has math as their worst subject: PEMDAS.
PEMDAS is an acronym used to mention the order of operations to be followed while solving expressions having multiple operations. PEMDAS stands for P- Parentheses, E- Exponents, M- Multiplication, D- Division, A- Addition, and S- Subtraction.
So we gotta do it in the proper order. And remember, if the number is written like 2(3) then its multiplication, as if it was written 2 x 3 or 2 * 3.
So we read 8/2(2+2) and need to do the following;
- Read the Parentheses of
(2 + 2)and follow the order of operations within them, which gets us 4. - Then we do
2(4)which is the same as2 x 4which is8 8 / 8is1.
The answer is 1. The old calculator is correct, the phone app which has ads backed into it for a thing that all computers were invented to do is inaccurate.
The problem with this is that the division symbol is not an accurate representation of the intended meaning. Division is usually written in fractions which has an implied set of parenthesis, and is the same priority as multiplication. This is because dividing by a number is the same as multiplying by the inverse, same as subtracting is adding the negative of a number.
8/2(2+2) could be rewritten as 8×1/2×(2+2) or (8×(2+2))/2 which both resolve into 16.
You left out the way it can be rewritten which most mathematicians would actually use, which is 8/(2(2+2)), which resolves to 1.
load more comments
(1 replies)
The problem is that the way PEMDAS is usually taught multiplication and division are supposed to have equal precedence. The acronym makes it look like multiplication comes before division, but you're supposed to read MD and as one step. (The same goes for addition and subtraction so AS is also supposed to be one step.) It this example the division is left of the multiplication so because they have equal precedence (according to PEMDAS) the division applies first.
IMO it's bad acronym design. It would be easier if multiplication did come before division because that is how everyone intuitively reads the acronym.
Maybe it should be PE(M/D)(A/S). But that version is tricky to pronounce. Or maybe there shouldn't be an acronym at all.
load more comments
(1 replies)
load more comments
(5 replies)
This is exactly why we have Reversed Polish Notation. When will people learn?
A fifteen year old version of myself somewhere inside just screamed in iptscrae induced frustration.
RPN Gang unite!
there's a setting in Qalculate! that asks if you want implicit multiplication to apply to the denominator or the numerator
I don't think you encounter this one very often, but the technically correct -2^2 = -4 has a higher chance of ruining your day.
load more comments
(10 replies)
8÷2(2+2)=2(2+2)÷2(2+2)
alternatively if 8÷2(2+2)=16 that means 2(2+2)=8÷16 in other words 8=0,5 which it isnt
your first line is correct, but while it looks like 1 (and it might be under different conventions), evaluating according to standard rules (left to right if not disambiguated by pemdas) yields
2(2+2)/2(2+2) = 2(4)/2(4) = 2*4/2*4 = 8/2*4 = 4*4 = 16
Using implicit multiplication in quotients is weird and really shouldn't happen, this would usually be written as 8/(2*(2+2)) or 8/2*(2+2) and both are much clearer
Your second argument only works if you treat 2(2+2) as a single "thing", which it looks like, but isn't, in this case
not much to refute in the argument of whether its 16 or 1 as its all a matter of convention in the end and ultimately the root of the argument is poor formatting of the expression, im used to implicit multiplication taking precedent and that 2(2+2)===2*(2+2) and that for my first argument having the same expression on 2 sides of a division sign automatically equals 1, but how come you find implicit multiplication in quotients weird? seeing as it happens literally all the time in equations, unless thats a difference in school systems or similar im unaware of
for fun also rewrote the expression into powers of 2 and indeed depending on how you go about implicit multiplication i end up with either 2⁰ or 2⁴, so for the sake of sanity i figure its best to just say x₁=1; x₂=16
It's weird because usually the people writing the expressions want to communicate clearly, and stuff like 1/2x is not immediately clear to everyone, so they write the 1/2 as a fraction.
The same expression on both sides of the division sign only reduce to one if they actually bind to the division sign, which is rarely an issue, but that is exactly the thing that is in question here. I think it's clear that 1 + 1/1 + 1 is 3, not 1, even though 1+1 = 1+1.
But as you said, of course, the evaluation order is just convention, you can just as well write everything in https://en.m.wikipedia.org/wiki/Reverse_Polish_notation
load more comments
(1 replies)
Ah damn it. It took me ages to find a calculator app that fits my needs..... And now I find out it works like the one on the right.
... the one on the right is correct.... that's a jank ass calculator on the left that doesn't know how to do order of operations 8/2×(2+2) 8/2x4 4x4 16
load more comments
(3 replies)
Is this HiPER Calc with ads? Did the free version have those?
view more: next ›