this post was submitted on 03 Dec 2023
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For anyone like me who has math as their worst subject: PEMDAS.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 written2 x 3or2 * 3.So we read
8/2(2+2)and need to do the following;(2 + 2)and follow the order of operations within them, which gets us 4.2(4)which is the same as2 x 4which is88 / 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.
EDIT: Turns out I'm wrong, but I haven't been told how or why. I'm willing to learn if people actually tell me, instead of call me wrong and keep it at that. I was told PEMDAS and did PEMDAS.
Well that's just wrong... Multiplication and division have equal priorities so they are done from left to right. So: 8 / 2 * (2 + 2)=8 / 2 * 4=4 * 4=16
This but unironically
Not quite, pemdas can go either from the left or right (as long as you are consistent) and division is the same priority as multiplication because dividing by something is equal to multiplying by the inverse of that thing... same as subtraction being just addition but you flip the sign.
8×1/2=8/2 1-1=1+(-1)
The result is 16 if you rewrite the problem with this in mind: 8÷2(2+2)=8×(1/2)×(2+2)
I've never had anyone tell me operations with the same priority can be done either way, it's always been left to right.
I've always heard it that way too but I think it is for consistency with students, imo Logically, if you are looking at division = multiplying by inverse and subtraction = adding the negative, you should be able to do it both ways. Addition and multiplication are both associative, so we can do 1+2+3 = (1+2)+3 = 1+(2+3) and get the same answer.
But subtraction and division are not associative. Any time you work on paper, 2 - 2 - 2 would equal -2. That is, (2-2)-2=0-2=-2. If you evaluate right to left, you get 2-2-2=2-(2-2)=2-0=2
Correct, subtraction and division are not associative. However, what is subtraction if not adding the opposite of a number? Or division if not multiplying the inverse? And addition and multiplication are associative.
2-2-2 can be written as 2 + (-2) + (-2) which would equal -2 no matter if you solve left to right, or right to left.
In your example with the formula from right to left, distributing the negative sign reveals that the base equation was changed, so it makes sense that you saw a different answer.
2 - (2 - 2) = 2 + ((-2) + 2) = 2
Implicit multiplication takes priority over explicit multiplication or division. 2(2+2) is not the same thing as 2*(2+2).
Admits they suck at math.
Tries to correct the math.
Is wrong.
I'm fuckin' dead rn 💀
Me searching the place for my old Ti83 after stumbling on this thread.
My partner: why are you even looking for this thing??
Me: Somebody on the Internet is WRONG.
My partner: Good enough, I'll help!
That's a keeper in my book.
I know, it's good to have someone in your life with priorities.
I happened to have my ti-83 plus next to me. I got 16!
YES finally, some sense in here. 🤣
I ended up downloading a Ti-83 emulator because mine has been devoured by the magical house gremlins.
Then I admit I'm wrong, I just don't get how PEMDAS/I got it wrong.
Short story, PEMDAS kinda sucks, because it has 4 levels of priority, but 6 letters:
M and D are the same level, priority is from left to right.
A and S are the same level, priority is from left to right.
Just tested this on a Ti-83 too.
8/2(2+2) = 16
My calculator gets 1. Weird.
My one big criticism of the Ti-83/84 is implicit multiplication. Ti says 1/2x is 0.5x when I needed the reciprocal of 2x.
I love you brought the TI truth lul
You got it right
Uh.. no the 1 is wrong? Division and multiplication have the same precedence, so the correct order is to evaluate from left to right, resulting in 16.
The real correct order is to use brackets to remove ambiguity.
Exactly, these types of problems are designed to make people confused and discuss PEMDAS and drive social media engagement.
not to be That Guy, but the phone is actually correct... multiplication and division have the same precedence, so
8 / 2 * 4should give the same result as8 * 4 / 2, ie 16The 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.
P E M D A S
vs
P E M/D A/S
The latter is correct, Multiplication/Division, and Addition/Subtraction each evaluate left to right (when not made unambiguous by Parentheses). I.e., 6÷2×3 = 9, not 1. That said, writing the expression in a way that leaves ambiguity is bad practice. Always use parentheses to group operations when ambiguity might arise.
Ignore the idiots telling you you're wrong. Everyone with a degree in math, science or engineering makes a distinction between implicit and explicit multiplication and gives implicit multiplication priority.
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.
PEMDAS evaluated from left to right. If you followed that you’d get 16. 1 is ignoring left to right.
You are correct. This is the right sequence of operations done here.
You're a lifesaver, thank you so much. I actually didn't know about PEMDAS, I was never taught it before...
They're actually wrong though.
There's 4 levels to PEMDAS, not 6.
Also,
https://www.symbolab.com/solver/step-by-step/8%5Cdiv2(2%2B2)?or=input
Like @[email protected] mentioned:
Ohh, I see. Thank you for clarifying, Math has always been the bane of my existence. x_x