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demwing

(16,916 posts)

174. To be accurate, PEMDAS could also be PEDMAS, or PEMDSA, or PEDMSA

Tue Jun 28, 2016, 02:00 PM

Jun 2016

but then creating a mnemonic would be awkward. Think of the term like this: PE(MD)(AS)

Multiplication and division hold the same position in the order of operations, as do addition and subtraction. After working the parentheticals and the exponents, you wouldn't do all multiplication before any division. You would do all multiplication and division before any addition and subtraction, and you would work those operations from left to right.

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A lot of people are having trouble with this math problem that requires some basic algebra [View all] sarisataka Jun 2016 OP

I don't understand why this is supposed to be hard? scscholar Jun 2016 #1

Quite a few people's algebra never included operator precedence seabeckind Jun 2016 #2

Which is why in my computer programs I just use lots of parentheses. n/t PoliticAverse Jun 2016 #7

Operator precedence Aerows Jun 2016 #23

Very significant in all calculations. BobTheSubgenius Jun 2016 #28

I disagree with the before computers part scscholar Jun 2016 #37

Incorrect. The order of operations has been around since algebraic notation, and probably before Android3.14 Jun 2016 #106

This message was self-deleted by its author Shrike47 Jun 2016 #3

It's a clickbait article oberliner Jun 2016 #5

The statistics are interesting, you have to admit. seabeckind Jun 2016 #9

Click bait articles often provide interesting information oberliner Jun 2016 #14

Dividing by a fraction 1939 Jun 2016 #26

I agree yeoman6987 Jun 2016 #71

It's hard if you don't know that you are suppose to do the division first... PoliticAverse Jun 2016 #6

Because we've forgotten the order of operations! TexasMommaWithAHat Jun 2016 #123

Thanks scscholar Jun 2016 #185

I used to code for actuaries - and made them give me everything with parenthesis hollysmom Jun 2016 #184

I actually got it right. Kingofalldems Jun 2016 #4

I did too, but I think many forget about the order of operations TexasBushwhacker Jun 2016 #169

I might suggest that it's a teacher/education problem seabeckind Jun 2016 #8

Hmmm. I took algebra in the mid-60's. I do not recall SheilaT Jun 2016 #60

As a former high school math teacher teacher educator, you're half right Android3.14 Jun 2016 #113

You didn't forget. seabeckind Jun 2016 #171

My UICSM course was a sort of "New Math", SheilaT Jun 2016 #173

It does not "require some basic algebra". Nye Bevan Jun 2016 #10

+x LongtimeAZDem Jun 2016 #13

lol auntpurl Jun 2016 #25

I am sorry, but you deserved more than one "lol" for this auntpurl Jun 2016 #76

Exactly. Further, you'd seldom run across something like that in real life. Hoyt Jun 2016 #22

I have seen division by a fraction quite often in real life (and you don't always get parenthses) 1939 Jun 2016 #29

Division by fraction, yes. This: 9 – 3 ÷ 1/3 + 1 = ? Not likely. Hoyt Jun 2016 #35

For Christ sakes. Division is the inverse of multiplication and 1 is the multiplicative identity! longship Jun 2016 #77

As written in the OP it is not division by a fraction. Lucky Luciano Jun 2016 #111

I was a nurse and I'm still a weaver Warpy Jun 2016 #151

Could you give me an example of something like 9 – 3 ÷ 1/3 + 1 = ? that you would run into as a Hoyt Jun 2016 #152

I would consider order of operations basic algebra NobodyHere Jun 2016 #68

exactly. it's pre-algebra, if you consider that as math that includes variables. Gabi Hayes Jun 2016 #159

I've seen enough of these to know this: IT DEPENDS UPON WHEN ONE WENT TO SCHOOL. I, for one, WinkyDink Jun 2016 #11

You don't need brackets to solve this! longship Jun 2016 #79

The problem here is the ambiguity. stone space Jun 2016 #83

No fucking need for them. There is no ambiguity here. longship Jun 2016 #86

Some folks insist emphatically that 27/9/3 = 9. stone space Jun 2016 #95

Equivalent operations go from left to right. immoderate Jun 2016 #139

Sorry mate - stone space is correct. Lucky Luciano Jun 2016 #112

I was speaking in general terms of all these alleged "brain-teasers." Get a grip. WinkyDink Jun 2016 #170

Or 4-3. LanternWaste Jun 2016 #175

absolutely correct AntiBank Jun 2016 #183

Ugh. Gormy Cuss Jun 2016 #118

PEMDAS isn't a newfangled thing. n/t lumberjack_jeff Jun 2016 #130

Obviously someone was sleeping during the order of operations lecture Kilgore Jun 2016 #12

Whippersnappers think the way they were taught is somehow superior to 1950's-1970's methods. WinkyDink Jun 2016 #15

That's one I have not come across Kilgore Jun 2016 #18

I'm a professional mathematician, and this would give me pause as you presented it. Donald Ian Rankin Jun 2016 #16

The problem is that 1939 Jun 2016 #30

That is not correct. athena Jun 2016 #49

Yes, / is used inline. Igel Jun 2016 #67

I don't have my Physics textbook anymore, but do have my "Theory of Simple Structures" textbook 1939 Jun 2016 #89

Yup, exactly what I did Godhumor Jun 2016 #34

I hope you use a lot of R or Python for data analysis! Lucky Luciano Jun 2016 #116

This message was self-deleted by its author progree Jun 2016 #44

+ struggle4progress Jun 2016 #54

In programming you always parenthesize so as of avoid future problems. bemildred Jun 2016 #93

Folks may disagree on the value of 3/1/3, but I hope that we can all agree that 3/1/3=27/9/3. stone space Jun 2016 #102

Wouldn't Americans write that as 1/3/3 = 9/27/3? N.T. Donald Ian Rankin Jun 2016 #120

You win! stone space Jun 2016 #126

It's not even algebra, it's basic arithmetic Ex Lurker Jun 2016 #17

Some people probably forget that dividing by 1/3 is the same as multiplying by 3. alarimer Jun 2016 #19

Is dividing by 1/4 the same as multiplying by 4, also? Forgive me, I'm a fine arts major. brush Jun 2016 #40

Yes. n/t PoliticAverse Jun 2016 #48

dividing by the fraction a/b is always the same as multiplying by the fraction b/a JustinL Jun 2016 #74

This message was self-deleted by its author Aerows Jun 2016 #84

Probably forgot "Please Excuse My Dear Aunt Sally". NutmegYankee Jun 2016 #20

BEMDAS is high level math now? whoa. nt Electric Monk Jun 2016 #21

It's poorly written teach1st Jun 2016 #24

You only need parentheses when the order of calculation is different from the usual rule. athena Jun 2016 #27

Thank you! BobTheSubgenius Jun 2016 #32

I'm terrible at math teach1st Jun 2016 #33

This is not a matter of opinion, and it's not just about tests. athena Jun 2016 #43

Here's one teach1st Jun 2016 #45

That says nothing about the rules of math themselves being ambiguous. athena Jun 2016 #47

+1 Person 2713 Jun 2016 #55

I wrote from an elementary teacher's perspective teach1st Jun 2016 #58

Thanks for clarifying. We agree on the fundamentals. athena Jun 2016 #66

Parsing conventions are just conventions, not mathematics. stone space Jun 2016 #82

In that case, you know what is meant from the context. athena Jun 2016 #87

I've always thought that physicists omit c in multiplicative expressions because c=1. stone space Jun 2016 #94

I suspect that the fact that the problem uses two different symbols for notating division... cemaphonic Jun 2016 #172

It depends on how and where you do most of your math Godhumor Jun 2016 #39

Math is math. Excel does not make up the rules of math. athena Jun 2016 #41

Quick, which is the way you'd write this problem using / Godhumor Jun 2016 #42

Again, this is not about Excel. athena Jun 2016 #46

I don't attack people on their math or programming knowledge Godhumor Jun 2016 #50

The question as it is posed in the OP is obviously a math problem athena Jun 2016 #52

You are obviously missing the point that several people in this thread are raising Godhumor Jun 2016 #57

This message was self-deleted by its author athena Jun 2016 #65

Indeed, as far as I can tell "/" is considered an acceptable symbol to denote division Chathamization Jun 2016 #69

Ok I have a phd in math and I disagree with you. Lucky Luciano Jun 2016 #109

My PhD in math tells me that 9 – 3 ÷ 1/3 + 1 = 9 – 27 ÷ 9/3 + 1. stone space Jun 2016 #114

Well they certainly are equal! Just a roundabout way to get there! Lucky Luciano Jun 2016 #117

I think we can all agree on the value of 2^2^2 as well. stone space Jun 2016 #122

Mind blown!!! LOL. nt Lucky Luciano Jun 2016 #124

A person with a PhD in physics, b.a. in math Duppers Jun 2016 #135

I agree with what you wrote except the outer parentheses are not needed. Lucky Luciano Jun 2016 #137

Exactly. Gormy Cuss Jun 2016 #121

1 Stinky The Clown Jun 2016 #31

It's a simple problem LWolf Jun 2016 #36

I got it right. forgotmylogin Jun 2016 #38

I got the right answer, but we learnt it as BOMDAS rather than BODMAS, and where he mentions it, he OnDoutside Jun 2016 #51

To be accurate, PEMDAS could also be PEDMAS, or PEMDSA, or PEDMSA demwing Jun 2016 #174

I took algebra as a high school freshman in 1965-66. 3catwoman3 Jun 2016 #53

We teach PEMDAS. apcalc Jun 2016 #61

The BEDMAS rule is dumb.. it simply causes confusion and errors. DCBob Jun 2016 #56

As several others have already pointed out, SheilaT Jun 2016 #59

No, you don't do it in order when there are no parentheses SickOfTheOnePct Jun 2016 #63

Enter 2 + 4 x 5 on your calculator. You will get 22, not 30, as the result, Nye Bevan Jun 2016 #70

On cheap calculators, you will get 30. Ms. Toad Jun 2016 #72

Where does this require algebra? Recursion Jun 2016 #62

there should be parentheses Enrique Jun 2016 #64

Order of operations. Learn them. backscatter712 Jun 2016 #73

Software developers are the people I'd expect to get it "wrong" most often. Donald Ian Rankin Jun 2016 #91

Who the hell knows? Parentheses are your friends. stone space Jun 2016 #75

Parsing conventions? SickOfTheOnePct Jun 2016 #88

Here's one parsing, which seems perfectly reasonable to me. stone space Jun 2016 #92

If you're really a mathematician SickOfTheOnePct Jun 2016 #96

Which parsing did you choose? I assume that you got either 9 or 1 as an answer. stone space Jun 2016 #97

I chose the only correct method SickOfTheOnePct Jun 2016 #98

So, does that mean that 27/9/3=9? stone space Jun 2016 #99

Wrong again SickOfTheOnePct Jun 2016 #100

If you claim that 3/1/3=3/(1/3)=9, you should also claim that 27/9/3=27/(9/3)=9. stone space Jun 2016 #101

I'm not claiming anything SickOfTheOnePct Jun 2016 #107

Do you agree that 3/1/3=27/9/3? stone space Jun 2016 #108

Sure SickOfTheOnePct Jun 2016 #115

Nope Lucky Luciano Jun 2016 #128

I suggest you go look at the video SickOfTheOnePct Jun 2016 #129

Point is that the equation as written in the OP is Lucky Luciano Jun 2016 #131

It's written exactly the same SickOfTheOnePct Jun 2016 #133

Sigh...you are dead wrong...it is a division operation not Lucky Luciano Jun 2016 #134

And says that 9 is incorrect SickOfTheOnePct Jun 2016 #155

equivalent operations (i.e. division) happen left to right without parentheses Lucky Luciano Jun 2016 #157

Another person who doesn't understand SickOfTheOnePct Jun 2016 #160

I officially give up - you would fail my class. nt Lucky Luciano Jun 2016 #161

You would fail people who got the correct answer - 1? SickOfTheOnePct Jun 2016 #162

Whatever dude. Lucky Luciano Jun 2016 #165

Nailed it... SidDithers Jun 2016 #119

+1, "with improper punctuation" I had to use order of precedence all the time in writing psuedo code uponit7771 Jun 2016 #168

+1, order of precedence semantics uponit7771 Jun 2016 #167

My 9th grade science teacher grilled us on the order of operation. Sam_Fields Jun 2016 #78

This thread absolutely proves DUers will argue about anything auntpurl Jun 2016 #80

Here's how to determine whether it's ambiguous Orrex Jun 2016 #81

I think the confusion comes in because Aerows Jun 2016 #85

Old math, new math, it's all pffffft to me lol Doremus Jun 2016 #90

Translating math to English, it clearly says GreatCaesarsGhost Jun 2016 #103

I am a mathematician, but had to click through to get it right. Lucky Luciano Jun 2016 #104

The factorial of 9 factorial is YUGE. stone space Jun 2016 #141

You talking about Trump's credit card debt? nt Lucky Luciano Jun 2016 #142

Think of it as 1939 Jun 2016 #164

No I get that...but strictly speaking... Lucky Luciano Jun 2016 #166

4th grade arithmetic Android3.14 Jun 2016 #105

An ambiguous question leads to different answers... SidDithers Jun 2016 #110

Yes KentuckyWoman Jun 2016 #146

It's a simple order of operations peoblem. Adrahil Jun 2016 #125

Clearly, some here are in need of some remedial mathematics: LongtimeAZDem Jun 2016 #127

I googled this edhopper Jun 2016 #132

Dividing by a fraction is the same as multiplying by its reciprocal. backscatter712 Jun 2016 #136

I know that edhopper Jun 2016 #140

That's a keyboarding issue demwing Jun 2016 #178

That's because the Google algorithm failed to recognize that the obelus indicated that the fraction LongtimeAZDem Jun 2016 #181

Just like Donald Trump, I have the best answer. The GREATEST answer! Binkie The Clown Jun 2016 #138

This message was self-deleted by its author stopbush Jun 2016 #143

Well, if you can't do basic math.... Adrahil Jun 2016 #148

This message was self-deleted by its author stopbush Jun 2016 #149

I'd disagree.... Adrahil Jun 2016 #150

This message was self-deleted by its author stopbush Jun 2016 #156

The answer is 42. nt Buns_of_Fire Jun 2016 #144

Wrong equation demwing Jun 2016 #180

I thought the answer was 1... TheDebbieDee Jun 2016 #145

This doesn't come as a surprise, honestly IgelJames4 Jun 2016 #147

Spoiler: applegrove Jun 2016 #153

I was told there would be no math. DemFromPittsburgh Jun 2016 #154

+1 for the SNL reference (nt) LongtimeAZDem Jun 2016 #179

Meanwhile, on DU I'm betting about 10% got it correct. L. Coyote Jun 2016 #158

Now test everyone with some boolean logic rickford66 Jun 2016 #163

Logic 2: Electric Boolean Orrex Jun 2016 #176

It's called parentheses, people. Warpy Jun 2016 #177

why is this ultra simple problem so hard for so many people? AntiBank Jun 2016 #182