this post was submitted on 26 May 2024

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503

a very emphatic answer (lemmy.blahaj.zone)

submitted 5 months ago by [email protected] to c/[email protected]

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[–] [email protected] 3 points 5 months ago

What enrages me is the pairing of "wrong" and "correct".

[–] [email protected] 2 points 5 months ago* (last edited 5 months ago) (1 children)

With pemdas correct if written, incorrect if spoken. Ignoring pemdas the opposite. And verbally if the exclamation is not spoken as factorial

[–] [email protected] 5 points 5 months ago (1 children)

4 factorial is correct lol

[–] [email protected] 3 points 5 months ago

Yee, I was in the midst of correcting myself since I was typing off my memory

[–] [email protected] 16 points 5 months ago (1 children)

I actually remember seeing this on my YouTube feed. I was pretty confused at first until I saw the factorial sign.

[–] [email protected] 6 points 5 months ago

OH!

[–] [email protected] 27 points 5 months ago (1 children)

And that kids name? Mathew Matician.

[–] [email protected] 2 points 5 months ago

The kid who got it wrong? Numbers McCountyFingers.

[–] [email protected] 15 points 5 months ago

Where is the bell curve

[–] [email protected] 43 points 5 months ago (3 children)

Throw up some brackets, you rage-baiting motherfucker!

[+] [email protected] 9 points 5 months ago* (last edited 1 month ago) (2 children)

[deleted]

[–] [email protected] 1 points 5 months ago (2 children)

Even your "BODMAS" isn't universal, lots of people learn "PEMDAS" or "BEDMAS"

At any level of mathematics after elementary school, you never see terrible expressions like this. Well, except for facebook and twitter

Take for example: 2/2*2 It is 0.5 or 2 depending on order. But if I were anything after high school (I was more complacent in high school, I guess) if someone gave me an arbitrarily solved equation or expression like this, I would be livid and raise hell at them for trying to do that.

[–] [email protected] 0 points 5 months ago (1 children)

Even your “BODMAS” isn’t universal, lots of people learn “PEMDAS” or “BEDMAS”

The rules are universal, only the mnemonics used to remember the rules are different

except for facebook and twitter

... and high school Maths textbooks, and order of operations worksheet generators, and...

2/2*2 It is 0.5 or 2 depending on order.

It's always 2. #MathsIsNeverAmbiguous

[–] [email protected] 0 points 5 months ago (1 children)

The rules are universal, only the mnemonics used to remember the rules are different

The rules and the acronyms describe different things. If you have to make more rules to say M and D are the same, and that you go left to right when you do them, then the basic rules you followed were flawed. The universal conventions of mathematics don't need these acronyms confusing people.

high school Maths textbooks

I haven't seen anything since early elementary school, not middle school, and certainly not high school. Regardless, if a textbook has it, it doesn't make it right at all. If the acronyms are useless to learn, having them in a textbook doesn't validate them.

and order of operations worksheet generators

...that's one of the two examples you used? Did you think about that before you typed it out?

It’s always 2. #MathsIsNeverAmbiguous

IT IS AMBIGUOUS IN THIS POST AND ALL EXAMPLES I HAVE SHOWN. That is the problem at hand.

There is no real problem solving in trying to decipher poorly written shit. It's the equivalent if English classes took time out to give students worksheets with "foder" written on them, and expecting students to find out if the writer meant "folder" or "fodder"- no sentence context, just following a list of "rules". It is not difficult to write mathematical expressions with clear context to how numbers relate, even with the lazy shortcuts and shorthand that mathematicians love.

[–] [email protected] 0 points 5 months ago

The rules and the acronyms describe different things.

No, they don't.

If you have to make more rules to say M and D are the same,

I didn't make more rules - that's the existing rules. Here's one of many graphics on the topic which are easy to find on the internet...

…that’s one of the two examples you used?

Yes. Did you try looking for one and ramping it up to the most difficult level? I'm guessing not.

IT IS AMBIGUOUS IN THIS POST

No, it isn't. Division before subtraction, always.

ALL EXAMPLES I HAVE SHOWN

None of those have been ambiguous either, as I have pointed out.

That is the problem at hand.

The problem is people not obeying the rules of Maths.

There is no real problem solving in trying to decipher poorly written shit

It's not poorly written. It's written the exact way you'd find it in any Maths textbook.

[+] [email protected] 1 points 5 months ago* (last edited 1 month ago) (1 children)

[deleted]

[–] [email protected] 0 points 5 months ago (1 children)

Yes, the fundamentals the same, higher orders come first. BUT...

-Multiplication comes before division in some forms, like PEMDAS. In the example I use, this changes the answer.

-When you apply an operation, you should specify what it is operating on. In all of these acronyms, addition comes before subtraction, but with a different example:

2 - 2 + 2

The minus sign only applies to the middle term, by convention. It is the equivalent of "adding negative two". You can quickly see that this expression is equal to 2.

But if you use one of these acronyms, you end with this expression evaluating to -2. I would say it is almost universally accepted that 2 is the correct answer, and -2 is incorrect. Basically, all these acronyms end up being useless waste of time.

I don't know if I conveyed this the first time, but, as a lover of pure mathematics, this is something that does not have application in life or in study. It's an utterly useless waste of time. There is never a case where someone give you numbers like this, where it is not clear what order the numbers should be applied in.

[–] [email protected] 1 points 5 months ago (1 children)

Multiplication comes before division in some forms, like PEMDAS. In the example I use, this changes the answer

If you have both multiplication and division then you do them left to right. PEMDAS doesn't mean multiplication first, nor does BEDMAS mean division first. It's PE(MD)(AS) and BE(DM)(AS) where the bracketed parts are done left to right.

you should specify what it is operating on

Left associativity means it always operates on the following term. i.e. terms are associated with the sign on their left.

The minus sign only applies to the middle term, by convention

By the rule of left associativity.

But if you use one of these acronyms, you end with this expression evaluating to -2

No it doesn't. How on Earth did you manage to get -2?

all these acronyms end up being useless waste of time

No they're not, but I don't know yet where you're going wrong with them without seeing your working out.

[–] [email protected] 0 points 5 months ago* (last edited 5 months ago) (1 children)

If you have both multiplication and division then you do them left to right. PEMDAS doesn’t mean multiplication first, nor does BEDMAS mean division first. It’s PE(MD)(AS) and BE(DM)(AS) where the bracketed parts are done left to right.

You are adding more rules to protect a convention that doesn't work and doesn't mention them to begin with. If all that matters is higher orders first, then why bother having an acronym? Just say "Brackets, then higher orders". Bam. Solved it with less words than any of the acronyms.

Left associativity means it always operates on the following term. i.e. terms are associated with the sign on their left.

As someone who studied mathematics, computer science, and engineering in university, I certainly don't you to tell me how to do bare bones arithmetic. I know operators apply to the numbers to their right. Everyone does. You jumped right on by the point.

With 2/2*2, you don't know if it is 2*2/2, or 2/(2*2). When you are dividing by numbers, you put them all in the denominator. If I had to put it in a line, I would at least do 2/(2)*2, to show what is in the denominator. If it is ambiguous, you have done it incorrectly.

By the rule of left associativity.

BY CONVENTION, as I said. You don't have to repeat what I said a second time.

No it doesn’t. How on Earth did you manage to get -2?

wow. geez. I wonder.

If you can't follow the steps guided for such a simple example, maybe we just shouldn't have this conversation. It's not like you could have tried in your head different orders to combine 3 numbers.

[–] [email protected] 0 points 5 months ago

You are adding more rules

I'm stating the existing rules.

If all that matters is higher orders first

I don't even know what you mean by that. We have the acronyms as a reminder of the rules, as I already said.

I know operators apply to the numbers to their right.

If you know that then how did you get 2-2+2=-2?

With 2/22, you don’t know if it is 22/2, or 2/(2*2)

Yes you do - left associativity. i.e. there's no brackets.

When you are dividing by numbers, you put them all in the denominator

Only the first term following a division goes in the denominator - left associativity.

BY CONVENTION, as I said. You don’t have to repeat what I said a second time.

I didn't. You said it was a convention, and I corrected you that it's a rule.

It’s not like you could have tried in your head different orders to combine 3 numbers.

addition first

2-2+2=4-2=2

subtraction first

2-2+2=-2+2+2=-2+4=2

left to right

2-2+2=0+2=2

3 different orders, all the same answer

[–] [email protected] -3 points 5 months ago (1 children)

It's perfectly reasonable to read this as both (40-32)/2 and 40-(32/2) anywhere past basic math.

[–] [email protected] 1 points 5 months ago

No, it isn't. Division before subtraction.

[–] [email protected] 32 points 5 months ago (1 children)

No actually the trick to this one is that Four-Factorial equals 24

So 40 - 16 = 24

[–] [email protected] 2 points 5 months ago

Aha! Fair enough.

[–] [email protected] 16 points 5 months ago (1 children)

This one's perfectly unambiguous without brackets, unlike the 1/2x stuff

[–] [email protected] 1 points 5 months ago

1/2x is also unambiguous. 2a=(2xa) by definition. Has done for at least 180 years. Terms

[–] [email protected] 6 points 5 months ago

it's wrong, because:

i would never ask a kid something like that
there is a question mark missing
i don't know any kids and they would probably just flip me off in that situation, which is okay, because they shouldn't talk to strangers

[–] [email protected] 91 points 5 months ago* (last edited 5 months ago) (1 children)

40-32/2 _ 4!

40-16 _ 2×3×4

30-6 _ 2×12

24 = 24

Checks out.

[–] [email protected] 55 points 5 months ago (3 children)

Depends if the kid said "four!" or "four factorial"

[–] [email protected] 12 points 5 months ago (1 children)

That’s how I say factorial though I just yell

[–] [email protected] 3 points 5 months ago

So Italians mathematicians put everything in factorial

[–] [email protected] 25 points 5 months ago

all maths must be said in a neutral tone lest you imply factorials

[–] [email protected] 12 points 5 months ago

Almost as if the joke relies on the fact that in written form those are the same.

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