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Author Topic: 7 – 4 + 3 x 0 + 1 = ?  (Read 43617 times)

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Kuildeous

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7 – 4 + 3 x 0 + 1 = ?
« on: July 16, 2012, 10:47:56 am »
+5

I am such a masochist sometimes.

Every so often, there is some question or poll or graphic on Facebook (and I'm sure other social media sites and forums) where someone asks a simple algebra question. This question comes in many flavors, but the one that I saw most recently was:

7 – 4 + 3 x 0 + 1 = ?

The author is challenging what the average person knows. The correct answer is, of course, 4. So many people out there insist that it's 1. After all, anything times 0 is 0. I've even seen some people claim the answer is 7, but I suspect that's a matter of glossing over the details and mistaking the multiplication for addition.

Whenever I see one of these, I feel compelled to help out. I read the comments, which are full of kids (at least I hope they're kids) screaming at each and calling each other retarded for not knowing that their answer is correct. And it drives me crazy. It really drives me crazy that someone who got the wrong answer is calling someone a moron for coming up with the right answer. Like a fool, I try to explain order of operations, but I get shouted down as well. It doesn't bother me that someone goofed or is simply not that knowledgeable, but it does bother me when that person refuses to even listen to the reasons why 4 is the correct answer. It's willful ignorance at that point.

It also doesn't help that the standard calculator doesn't do order of operations. You have to have a "scientific" calculator. That annoys me too. I can see the purpose of the adding machine, but it just encourages bad math. Even the Windows calculator has a standard setting that ignores order of operations. I believe it's the default calculator, so the layperson probably doesn't even know that there is a more accurate setting (fun fact: The actuarial exams in the early 90s required the use of a calculator that looked similar to a scientific calculator but in fact did not use the order of operations either—madness).

I think the next time I feel the need to step into one of these warzones, I will include directions on how to use the scientific mode of the Windows calculator. It's actually very difficult to disabuse someone of his wrong answer when he can just type in the formula and see for himself that the answer is clearly 1.

Sorry, I felt the need to rant. I figured that aside from a math forum, you guys could relate, even though you probably don't suffer my obsessive need to correct people on the internet.
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DStu

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #1 on: July 16, 2012, 10:57:52 am »
+5

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Ozle

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #2 on: July 16, 2012, 10:58:37 am »
0

You mean the answer isn't 7?

And its not on the normal calculator because normal calculations dont really need BODMAS. You only really need it if you are in a scientific job, and if you are in a scientific job, why wouldn't you have a scientific calculator?

But the lack of knowledge thing is annoying, I agree


http://imgs.xkcd.com/comics/duty_calls.png
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Ozle

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #3 on: July 16, 2012, 11:00:01 am »
0

Also, could be worse, you could be one of these people!

http://www.bbc.co.uk/news/magazine-18833763
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ehunt

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #4 on: July 16, 2012, 11:00:08 am »
+4

I disagree with the convention that multiplication takes precedence over addition when it's written with a times sign, and I wish we had a left-to-right convention. (That's all it is, by the way, a convention. We could have a convention that any string is meaningless unless it has enough parentheses to specify the order of operations, but that would be annnoying, so instead we have to choose another one.) That being said:

1. For some reason we as a society think it's important to make middle schoolers feel stupid by teaching them arbitrary conventions and then labeling them as bad at math for not being able to remember/follow them. Given that everybody had to learn this unfortunate convention, I guess we should keep using it, for the same reason we don't switch to the metric system. So, fine, the answer to your question is 4.

2. I do agree with the convention that multiplication should take precedence over addition in an expression like

8 + 5y

or

12 + 7(3)

as I feel it's intuitive in these contexts, just not when you denote multiplication by X or *.
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jonts26

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #5 on: July 16, 2012, 11:01:12 am »
+3

You mean the answer isn't 7?

And its not on the normal calculator because normal calculations dont really need BODMAS. You only really need it if you are in a scientific job, and if you are in a scientific job, why wouldn't you have a scientific calculator?

But the lack of knowledge thing is annoying, I agree


http://imgs.xkcd.com/comics/duty_calls.png

Wait, what is BODMAS? Is that the english version of PEMDAS?
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theory

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #6 on: July 16, 2012, 11:01:56 am »
+2

Order of operations seems like such a silly thing.  It isn't a property intrinsic to the number system, but just a set of rules for interpreting our chosen method of expressing numbers and operations.  There's no particular reason multiplication has to come before addition, just convention.
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Ozle

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #7 on: July 16, 2012, 11:04:31 am »
+1

You mean the answer isn't 7?

And its not on the normal calculator because normal calculations dont really need BODMAS. You only really need it if you are in a scientific job, and if you are in a scientific job, why wouldn't you have a scientific calculator?

But the lack of knowledge thing is annoying, I agree


http://imgs.xkcd.com/comics/duty_calls.png

Wait, what is BODMAS? Is that the english version of PEMDAS?

Brackets over Division, Multiplation, addition, Subtraction.
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jonts26

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #8 on: July 16, 2012, 11:04:43 am »
+3

Sometimes it's not that the speicfic convention is any better than another one, but that it's just much better to have some sort of convention. Like driving on the right (or left) side of the road.
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WanderingWinder

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #9 on: July 16, 2012, 11:04:57 am »
+2

Order of operations seems like such a silly thing.  It isn't a property intrinsic to the number system, but just a set of rules for interpreting our chosen method of expressing numbers and operations.  There's no particular reason multiplication has to come before addition, just convention.
Multiplication coming before addition is more objectively better than the reverse than Fahrenheit is objectively better than Celsius.

jonts26

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #10 on: July 16, 2012, 11:05:40 am »
0

Brackets over Division, Multiplation, addition, Subtraction.

And what about exponents. What do I do with all these exponents!
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Ozle

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #11 on: July 16, 2012, 11:06:56 am »
0

Brackets over Division, Multiplation, addition, Subtraction.

And what about exponents. What do I do with all these exponents!

By the time I knew about exponents I was old enough not to need silly words to remember how to do things *grins*
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DStu

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #12 on: July 16, 2012, 11:15:16 am »
+2

Quote
For some reason we as a society think it's important to make middle schoolers feel stupid by teaching them arbitrary conventions and then labeling them as bad at math for not being able to remember/follow them.
From my (limited) experience the problem with math for most people is that they only see a string of characters, try to remember something that looks similar and now do the same thing they have done with the similar looking thing.
Instead of trying to understand what is written there, and once you would do this, there is not much point in arguing. Either you think, if someone writes 7-4+3x0+1, they mean 'take 7, substract 4, add 3 multiply everything with zero and finally add 1'. Then this is probably not what the person has meant, but at least you should likely to be convinced by someone who says: 'Hey, remember, multiplication has higher priority than addition, so someone who writes 7-4+3x0+1 probably means "take 7, substract 4, add the result of the mulitplication 3 and 0, and add 1". Jo, thanks, I have forgotten kkthxbb.

Instead people think "OMG, math, ... PANIC!!!. OK, there IS a "x0", and EVERYTHING x0 is ZERO !!!!!!11111eleven11!!!!!". 'Hey, but remember, multiplication has higher.-.' "EVERTHING ... ZERO LOLWUT!!!!11!".


On the other hand, from other experience, most people on the internetz discussing these topics are trolls.
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Kuildeous

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #13 on: July 16, 2012, 11:33:50 am »
+4

Order of operations seems like such a silly thing.  It isn't a property intrinsic to the number system, but just a set of rules for interpreting our chosen method of expressing numbers and operations.  There's no particular reason multiplication has to come before addition, just convention.

I think that multiplication over addition is not that arbitrary.

Purchase orders use the rule all the time. If you say that you bought 5 apples at 20 cents apiece and 3 oranges at 30 cents apiece, you naturally would work it out as 5*20 + 3*30. Any time you deal with groups of similarly quantified objects, you go into PEDMAS mode, even if it's really DMAS mode. It's a convenient method because grouping works very well with it.

I do sometimes feel like the "Duty Calls" guy. With this one, I know better than to get involved with a flame ware there. I can only state my case. If others cannot see it, then they either are not far enough along in their algebra to know the difference or are too far gone. The math tutor in me just cannot let these errors persist, but I'm not getting paid to argue on the internet.

Sadly, DStu, I don't think many of these people are trolls. Maybe I'm just naοve, but I've seen enough people struggle with math, that I'm willing to believe that they honestly don't know. But perhaps I have been trolled very well. People who create these topics, however, probably are trolling, but I don't mind bringing these problems to the forefront. Whatever it takes to make people think
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eHalcyon

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #14 on: July 16, 2012, 12:17:38 pm »
0

You're all crazy.  The acronym is BEDMAS, E for Exponents.

But I guessed that Ozle's O was "Orders", which means the same thing.  And searching on Google seems to confirm that, though Ozle disagrees?

I think I liked PEDMAS more because () are technically not brackets.  But I learned what I learned!
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Ozle

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #15 on: July 16, 2012, 12:21:57 pm »
0

You're all crazy.  The acronym is BEDMAS, E for Exponents.

But I guessed that Ozle's O was "Orders", which means the same thing.  And searching on Google seems to confirm that, though Ozle disagrees?

I think I liked PEDMAS more because () are technically not brackets.  But I learned what I learned!

I definately learnt it as Over, but as I said I learnt it very young before I knew about powers and such!
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Davio

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #16 on: July 16, 2012, 12:35:06 pm »
0

In a math book I once had there were three kinds of brackets: parantheses, square brackets and curly brackets!

It was MADNESS I tell you!
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eHalcyon

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #17 on: July 16, 2012, 12:35:38 pm »
0

In a math book I once had there were three kinds of brackets: parantheses, square brackets and curly brackets!

It was MADNESS I tell you!

(parentheses)
[square brackets]
<angle brackets>
{braces}
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shMerker

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #18 on: July 16, 2012, 12:43:36 pm »
0

Braces is the plural of bracket. I think as long as we're nit-picking math we should nit-pick vocabulary too.
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gman314

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #19 on: July 16, 2012, 12:47:01 pm »
0

You're all crazy.  The acronym is BEDMAS, E for Exponents.

But I guessed that Ozle's O was "Orders", which means the same thing.  And searching on Google seems to confirm that, though Ozle disagrees?

I think I liked PEDMAS more because () are technically not brackets.  But I learned what I learned!

I went to a French immersion school until high school when I switched to an English school. In French I learned PEDMAS = Parentheses, Exponents, Division, Multiplication, Addition, Soustraction. (Now that I type it out, I'm surprised that all the words are the same except for subtraction and a missing accent in Parentheses.)

In English, I learned BEDMAS = Brackets, Exponents, Division, Multiplication, Addition, Subtraction. It really just seems that the instruction of arbitrary conventions has also become arbitrary.
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Grujah

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #20 on: July 16, 2012, 12:47:52 pm »
+3

We should just use
Reverse Polish Notation
http://en.wikipedia.org/wiki/Reverse_Polish_notation

Cuz its the best, easiest to implement, and needs no brackets.
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Ozle

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #21 on: July 16, 2012, 12:48:10 pm »
+1


In English, I learned BEDMAS = Brackets, Exponents, Division, Multiplication, Addition, Subtraction. It really just seems that the instruction of arbitrary conventions has also become arbitrary.

Surely you learnt it in Maths......BADOOM TSCH!
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eHalcyon

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #22 on: July 16, 2012, 12:48:48 pm »
0

Braces is the plural of bracket. I think as long as we're nit-picking math we should nit-pick vocabulary too.

Source?  I've always learned that braces refer to {}, and we say "square/angle braces" sounds super weird.  Wikipedia says this is common in the US, which makes me a little wary because I'm Canadian. ;)
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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #23 on: July 16, 2012, 12:49:48 pm »
0

We should just use
Reverse Polish Notation
http://en.wikipedia.org/wiki/Reverse_Polish_notation

Cuz its the best, easiest to implement, and needs no brackets.

Ie, your equation would translate into:

7 4 - 3 0 * + 1 +

(to used to mafia so I just doublepost instead of editing in forums too)  :'(
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eHalcyon

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Re: 7 – 4 + 3 x 0 + 1 = ?
« Reply #24 on: July 16, 2012, 12:52:16 pm »
+1


In English, I learned BEDMAS = Brackets, Exponents, Division, Multiplication, Addition, Subtraction. It really just seems that the instruction of arbitrary conventions has also become arbitrary.

Surely you learnt it in Maths......BADOOM TSCH!

There was this BBC show called "Look Around You", which was a parody of those grainy classroom instructional videos.  There was one episode for Maths.  I thought the s was just to make it sound funnier... didn't realize it was the Queen's English.  We just call it "Math" in North America.

I really wish I could link it, but most of the Look Around You videos appear to have been removed from Youtube.
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