I don’t think “two-dimensional number system” is something you’d hear mathematicians say
I teach Maths and would’ve thought that was referring to the Cartesian plane.
💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱
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Cake day: November 25th, 2023
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I’m gonna track down all my HS math teachers and punch each and every one of them in the mouth.
Understandable if you’re in the U.S., where Maths teachers don’t have to have any Maths qualifications. Other places, where you do have to have Maths qualifications, we teach this.
Where accuracy is important, since we almost always have a calculator with us now, that’s a no-brainer.
Unfortunately most calculator apps were written by no-brainers who didn’t check they had their Maths correct. If you need accuracy then get a name brand like Sharp or Casio.
May as well just get out the calculator app to make sure
Calculator apps get order of operations questions wrong because of programmers who were too lazy to check they had their Maths correct
My point with those numbers is to just use a calculator.
My point is avoid calculator apps like the plague. Use name brands like Sharp or Casio.
Why 2nd guess anything?
Guess what the programmer of your calculator app did 😂
Wow, that’s nice! I like it
It’s called grouping. It’s part of the curriculum here. Break the arithmetic into easily calculated groups.
I just hope that you are not starting grading your students with the phrase “You’re absolutely right!”
I’m not in the U.S. no. We still require teachers to be qualified here (Masters)! 😂
There’s nothing wrong with calculators
There is if you’re talking about calculators on phones, etc. Almost all of them give wrong answers to order of operations questions because the programmer didn’t bother checking their Maths first. It’s so bad that the Windows calculator in Standard mode says 2+3x4=20. Stick to name brands like Sharp and Casio. They have money invested in the success of their products, so they take more care to make sure it’s correct!
Yes, 47% of 47 is certainly much easier to determine
And your real life example of a 47% discount on a $47 item is… where exactly?
Yeah, now calculate 6% of 36
6x3x10 + 6x6, move decimal point 2 places to the left
Replies itt make me believe that everyone on Lemmy is a chatbot
I’m a Maths teacher :-)
people forget that percent literally means per 100 or /100
Yes
the of is standing in for multiplication
No. The M is for Multiplication. O is for Order, as in “to the order of”, as in Exponents.
6/100 * 50 = 50/100 * 6
=6x5 /10 (2 zeroes cancel out)
I just think the symbol “%” algebraically means 0.01
Warm. It actually means “per 100”, hence the slash to represent a vinculum and the 2 zeroes. Of course in decimal that converts to 0.01.
Yeah stuff like that really ain’t it
Yes it is
It works in a few use cases,
It works in every case where you have multiplying and dividing, including fractions and percentages
but is objectively wrong
No it isn’t
detracts from understanding the topic properly
Enhances it actually
That’s why I teach percentages as the fractions they are.
Sounds like you’re only teaching as much as you understand. Try understanding more. Students love the tricks that make Maths easier, including this one.
01·2 months agothe proper way is to group it as 1+(-2)+3
No it isn’t.
you can do it in any order
You can do it in any order anyway
left to right 1-2+3=-1+3=2
addition first 1+3-2=4-2=2
subtraction first -2+1+3=-1+3=2
right to left 3-2+1=1+1=2
What I meant with ““rule”” is the meme questions pray on people not understanding/remembering what the actual rules are
And you showed that you were one of them. Every answer you got other than 4 was wrong, because you didn’t understand the rules. spoiler alert: doing it in different orders never means add brackets to it. Addition first for 10-1+1 is 10+1-1, not 10-(1+1). See previous textbook example
why “left to right” conventions exist
They exist because people like you make mistakes when you try to do it in a different order. Either learn how the rules work or stop spreading disinformation. Well, you should stop spreading disinformation regardless.
I fully agree that if it comes down to “left to right”
It never does
But I’ve just shown why that “rule” is a common part
No you didn’t. You showed you didn’t understand the rules. Doing addition first for 10-1+1 is 10+1-1, not 10-(1+1). It literally means add all positive numbers together first, which are +10 and +1, as per Maths textbooks…
Note in the above simplification of the coefficients we have 6-11+5-7+2=6+5+2-11-7=13-18=-5, and not, as you claim 6-(11+5)-(7+2)=6-16-9=-19
because it is so weird and quite esoteric
It’s a convention, not a rule, and as such can be completely ignored by those who understand the rules. See literal textbook example
You teach how to solve equations, but not the fundamentals
Nope. We teach the fundamentals. Adults not remembering them doesn’t mean they weren’t taught. Just pick up a Maths textbook. It’s all in there. Always has been.
Fundamentals, most of the time, are taught in universities
No they’re not. They only teach order of operations from a remedial point of view. Most of them forget about The Distributive Law. I’ve seen multiple Professors be told by their students that they were wrong.
it’s not really math in a sense that you don’t understand the underlying principles
The Constructivist learners have no trouble at all understanding it.
Nope.
Yep!
There’s only commutation, association, distribution, and identity.
And many proofs of other rules, which you’ve decided to omit mentioning.
It doesn’t matter in which order you apply any of those properties, the result will stay correct
But the order you apply the operations does matter, hence the proven rules to be followed.
2×2×(2-2)/2
Notably you picked an example that has no addition, subtraction, or distribution in it. That’s called cherry-picking.
Completely different order, yet still correct
Yep, because you cherry-picked a simple example where it doesn’t matter. It’s never going to matter when you only pick operations which have the same precedence.
My response to the rest goes back to the aforementioned
…cherry-picking.
01·2 months agoNo, I am saying you are wrong
And textbooks, calculators, accountants, and @sxan@midwest.social, who also explicitly pointed out that what you did was 10-(1+1). I see you didn’t read the textbook either then.
No one else
Nope, also all the other parties listed above, who all agree with me
The saddest, and funniest, part is that you are so egotistical that you don’t see why you are wrong
That would be you again, after it has been explained to you many times, by me, other commentators, and Maths textbooks.
Maybe you will get it one day, but I won’t be there for it
Again that applies to you only, the only one here who thinks 10-1+1=8 when doing addition first.
Self reflection is good.
How do you know when you haven’t tried it yet? If you had, you would realise you also owe @cabron_offsets@lemmy.world an apology too
I know it is wrong, which is why I am telling you what my mistake was originally
But failing to understand what your actual mistake was, coming up with -1+1=-2, and not -1+1=-0
The fact that you still don’t get it demonstrates your complete lack of understanding
That would be you, the one who thinks order matters, and that -1+1=-2, not -0.
Order does matter
Nope!
+10-1+1=10
+10+1-1=10
-1+10+1=10
+1+10-1=10
+1-1+10=10
-1+1+10=10
Put those all into a calculator, and/or ask an accountant about it.
that order is left to right.
And yet, going RIGHT TO LEFT +1-1+10=0+10=10, same answer… though I have no doubt you think it’s +1-1+10=+1-11=-10
The original equation is written correctly
and 10-(1+1) isn’t, hence your continued wrong answer
My mistake was doing the addition before the subtraction when the equation reads 10 - 1 + 1
No, your mistake was doing 10-(1+1) where the question reads 10-1+1, and not +10+1-1 <== this is addition first, you add all the positive numbers together first, then do the negative numbers This is literally the textbook way to do it
According to you 6a²b-11a²b+5a²b-7a²b+2a²b=6a²b-16a²b-9a²b=-19a²b, and yet the textbook quite clearly states it’s -5a²b, which is because it’s 6a²b+5a²b+2a²b-11a²b-7a²b=13a²b-18a²b, and NOT 6a²b-(11a²b+5a²b)-(7a²b+2a²b)
10-(1+1)=10-1-1 which is what you did, which is not 10-1+1. You “added” 1 to -1, and got -2 instead of 0
How are you still not getting this?
It’s not me who’s not getting it.
No it wasn’t.
Yes it was. Read the textbooks.
The original equation is written correctly but the logic is incorrect
No your logic is incorrect. You’re incorrectly adding brackets to it.
in order to make it work the way I declared you have to do the equation x - y + z doing the y + z first
By putting it in brackets which is not how addition is done first. Doing addition first for x - y + z is x + z - y, not x - (y + z)
which was the mistake doing addition then subtraction
No, the mistake was you put the addition in brackets, -(1+1)=-2, not -1+1=+1-1=0. As per the textbook, the sum of any 2 numbers can only have 1 value. That 1 value for -1 and +1 is 0. -1+1=0, +1-1=0, not -1+1=-2
doing addition then subtraction instead of addition and subtraction in order from left to right
The rules are you either do addition then subtraction, OR you do left to right. There is no such thing as addition then subtraction left to right.
Addition then subtraction 10+1-1=11-1=10
Left to right 10-1+1=9+1=10
What you did 10-(1+1)=10-2=8
I see you are still being a bad teacher
says bad student, who didn’t try what the teacher said to try
who refuses to listen
that would be you again. You didn’t try it on a calculator, you didn’t ask an accountant. You didn’t even read and understand my examples. Read the textbook - it’s not just me telling you this.
I am not continuing with you
Because you’re unwilling to admit you’re wrong and refuse to try what the teacher and textbook have told you to do, and also refuse to ask an accountant about it
The fact that you still don’t get it demonstrates bad faith
Nope, that’s you again. You’re even arguing with literal textbook examples.
willful ignorance, and an unwarranted superiority complex
Also you, thinking you’re above Maths teachers, calculators, accountants, and Maths textbooks. According to you all of us are wrong, and only you are right. Get a grip
10-1+1=10 only if you don’t the addition first 1 + 1 = 2 - 10 = 8
Nope, yet again you just did 10-(1+1), which is wrong for 10+1-1. It gives 10 in any order. 10+1-1=11-1=10 <== did addition first, got 10. Accountants would have a nightmare if order mattered. “Did we receive this payment first, or this invoice? The order matters! ARGH!”
which was my mistake, which I already stated.
No, your mistake was adding brackets, 10-(1+1) ISN’T how to do addition first. 10+1-1 is. Ask an accountant! 😂 As you discovered 10-(1+1)=10-1-1, which isn’t 10+1-1, nor 10-1+1. 10-1-1=8, which is what you did - 10-1-1=10-(1+1) - 10-1+1=10, 10+1-1=10.
I see you still didn’t try it on a calculator yet then
Enjoy the egg on your face bud
None on my face. My students do very well in their tests. How about you? BTW try it on a calculator and guess what answer you’ll get. hint: it’ll be the same answer regardless of which order you do it 😂
To save you some trouble, here’s the results form my calculator…
10+1-1=10
10-1+1=10
-1+10+1=10
+1+10-1=10
-1+1+10=10
1-1+10=10
Quick and dirty and accurate is 38=40-2. So 38x37=(40-2)x37=40x37-2x37=1480-74=1406