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Okay, we all remember the mathematical order of operations from school, right?

If not, here's a reminder: In the US it's PEMDAS (Parenthesis, Exponents, Multiplication/Division, Addition/Subtraction) whereas in the UK it's BEDMAS (Brackets, Exponents, Division/Multiplication, Addition/Subtraction). I have no idea which is used in Canada and Australia, but I'm willing to bet BEDMAS.

There's no functional difference between the two, just that some different terminology is used (i.e. parenthesis vs brackets). The order of operations tells you what order to process the equation. When it comes to items that are separated by a slash, like addition/subtraction, do whichever of those two come first, but they're considered on equal footing in operational order.

Anyway... there was a math problem listed on Facebook that more than a few people got wrong, not because they're idiots, but because they've forgotten basic mathematical principles.

I'd like to see how many here get the right answer. A lot of people wrote that the answer is either 36 or 48, both of which are incorrect. The right answer is 17.

Here's the math problem:

Nice, thanks for sharing ! I make it 16, not 17Here it's Meneer Van Dale Wacht Op Antwoord (that's Mr Van Dale is waiting for an answer).
(edit - just looked into it and found it's outdated since the W (root) is no longer behind V and D (multiplication and division) and brackets weren't included in our old mnemonic. Currently the following one is being taught: Hoe Moeten Wij Van Die Onvoldoendes Afkomen?)

When I went shopping for my first high school calculator, the attendant showed us it was a good calculator by entering 2+2x3 and getting 8 as an answer (followed by my dad being confused saying it should be 12, then me explaining, then him shushing me.)

Here in Canada it's BEDMAS too. I also get 16 with my quick math not 17.

Because I despise math, I know I am wrong, and am one of those people that would come out to 48.

I'd need to cheat and break out a math book to remember the proper order of doing those.

Yep, 16 here.

Alternately, removing the picture placeholders and looking at it strictly algebraically:

Solver for d:

a + a + a = 18
a + b + b = 10
b + a - c = 4
c + b × a = d

========================================

BBP wrote: ↑Sat Nov 27, 2021 4:37 pm When I went shopping for my first high school calculator, the attendant showed us it was a good calculator by entering 2+2x3 and getting 8 as an answer (followed by my dad being confused saying it should be 12, then me explaining, then him shushing me.)

In my chemistry and physics courses back in the '80s and '90s, we used to refer to calculators that followed PEDMAS (or BEDMAS) generically as "scientific" calculators.

Most calculators for sale are of the "dumb" variety, and I fully expect that they will NOT follow PEDMAS when using them...

Yup, it's 16 for me as well. Here's how I did it, using goatmeal's algebraical equations (and since a, b and c must be a constant value):


a. a = 18 / 3 = 6.

b. b = (10 - 6) / 2 = 2.

c. If a = 6 and b = 2, then c = 4.

d. 4 + (2 x 6) = 16.


I learned this in Israel (so it was neither BEDMAS nor PEDMAS), but I don't mind maths.

goatmeal wrote: ↑Sat Nov 27, 2021 5:44 pm In my chemistry and physics courses back in the '80s and '90s, we used to refer to calculators that followed PEDMAS (or BEDMAS) generically as "scientific" calculators.

Most calculators for sale are of the "dumb" variety, and I fully expect that they will NOT follow PEDMAS when using them...

Nice. I did several programming and engineering courses, so I had to deal with algebra and binary/octal/hexadecimal systems, and others of that kidney. Trigonometry still trips me up, though.

I don't understand how ANY calculator doesn't follow PEDMAS/BEDMAS. Something like this shouldn't be up for debate!

Rath Darkblade wrote: ↑Sat Nov 27, 2021 7:26 pm I had to deal with algebra and binary/octal/hexadecimal systems, and others of that kidney. Trigonometry still trips me up, though.

In high school, I got up to Trig. (I can't recall my final score, but it was probably a "C" - Average - because there's no way I got higher, and my father would have hung me if I got lower).
I should have, honestly, never got passed Geometry.
I remember a some of it - but honestly, my dislike for all things math is unreasonable.

Ironically, I love D&D - which has a lot of math in it.

Maybe if they'd made math class more like D&D, I'd have loved it more.

Schools often make subjects dry and uninteresting, because they need to teach you enough to pass the exam. Some teachers would love to teach more if they could, but kids being kids, it's sometimes hard enough just to keep discipline. (Of course, some teachers don't care - for a variety of reasons. "I got tenure, why should I care?" or "The kids don't care, so neither can I").

I had to take history in school, and I can only remember maybe two or three things from that. Ironically, I almost have my own library of history books now.

Rath Darkblade wrote: ↑Sat Nov 27, 2021 8:25 pm Schools often make subjects dry and uninteresting, because they need to teach you enough to pass the exam. Some teachers would love to teach more if they could, but kids being kids, it's sometimes hard enough just to keep discipline. (Of course, some teachers don't care - for a variety of reasons. "I got tenure, why should I care?" or "The kids don't care, so neither can I").
I had to take history in school, and I can only remember maybe two or three things from that. Ironically, I almost have my own library of history books now.

It's pretty true - I remember back in High School, I was actually interested in US History (specifically) - I loved all those old drawings from back then that really helped capture my attention.
But I feel like it was always just moving to the next thing, even if I wanted to stop and study more of one specific area.
Ironic, now? I can barely tell you too much about US History. But the history of the Forgotten Realms or Dragonlance? Memorized.
I think that's why one of the first things I do when I create a D&D world is start with the history - because that's the foundation of the world - and build out and edit from there.
Not to veer this off topic.

I still hate math.

I don't remember the order of operations being referred to by an abbreviation, but I do remember the mnemonic device: Please Excuse My Dear Aunt Sally.

At first I got 16, but then I realized that there are a different number of bottles in the expressions: 6 in the first and second and fourth and 7 in the third. This gives you the correct answer of 17 and honestly is kind of cheating. You will get it answer wrong if you do the operations correctly and just assume the bottles are the same in all 4 expressions.

goatmeal wrote: ↑Sat Nov 27, 2021 5:44 pm
In my chemistry and physics courses back in the '80s and '90s, we used to refer to calculators that followed PEDMAS (or BEDMAS) generically as "scientific" calculators.

Most calculators for sale are of the "dumb" variety, and I fully expect that they will NOT follow PEDMAS when using them...

Rath Darkblade wrote: ↑Sat Nov 27, 2021 7:26 pm Nice. I did several programming and engineering courses, so I had to deal with algebra and binary/octal/hexadecimal systems, and others of that kidney. Trigonometry still trips me up, though.

I don't understand how ANY calculator doesn't follow PEDMAS/BEDMAS. Something like this shouldn't be up for debate!

Unless the calculator was a graphing calculator, most calculators I know of only did one operation at a time. So it was up to the person to get the order of operation right. Scientific calculators were just ones that did the trig functions and logarithms and such.

If people don't like learning the order of operations, we could always go to Reverse Polish Notation (or Postfix): 2+2x3 becomes 2 2 3 x +. Never any confusion.

notbobsmith wrote: ↑Sat Nov 27, 2021 11:43 pm I don't remember the order of operations being referred to by an abbreviation, but I do remember the mnemonic device: Please Excuse My Dear Aunt Sally.
At first I got 16, but then I realized that there are a different number of bottles in the expressions: 6 in the first and second and fourth and 7 in the third. This gives you the correct answer of 17 and honestly is kind of cheating. You will get it answer wrong if you do the operations correctly and just assume the bottles are the same in all 4 expressions.

Excellent eye.

And that's probably why 6 bottles = 6. So they could intentionally make people "see" six in one of those, when it's actually 7 - because each bottle (since there's 6 bottles and it equals 6 total, means each bottle is 1).

notbobsmith wrote: ↑Sat Nov 27, 2021 11:43 pm

Rath Darkblade wrote: ↑Sat Nov 27, 2021 7:26 pm Nice. I did several programming and engineering courses, so I had to deal with algebra and binary/octal/hexadecimal systems, and others of that kidney. Trigonometry still trips me up, though.
I don't understand how ANY calculator doesn't follow PEDMAS/BEDMAS. Something like this shouldn't be up for debate!

Unless the calculator was a graphing calculator, most calculators I know of only did one operation at a time. So it was up to the person to get the order of operation right. Scientific calculators were just ones that did the trig functions and logarithms and such.

True, back in my day they were called "Scientific Calculators" that were required for some classes.

To everyone who got the answer of 16... look at the third sequence again. There are SEVEN bottles, not SIX. Each bottle individually counts as ONE. This means the answer is in fact 17.

6 + 6 + 6 = 18
6 + 2 + 2 = 10
2 + 7 - 5 = 4
5 + 2 x 6 = 17

Also, for some odd reason, one of the bottles in the last sequence has a full red circle on its label instead of the half-red/half-white circle on the labels of all the other bottles. I'm not sure if that's a mistake or just some sort of inside joke, but it doesn't seem to matter as far as the actual equation goes.

As for scientific/graphing calculators... who didn't have a TI-85 or TI-86?

Sigh ... notbobsmith is right - that IS cheating. *pouts comically*

My eyesight isn't the best (I've had to wear glasses since an early age), and lately it's getting worse. But yes, I assumed there would always be 6 bottles. You know what they say about assumptions. =(

Still, at least I didn't fail the PEDMAS/BEDMAS thing. (That's not saying much, though, since I learned that in first grade...)

Bah nailed us all.

notbobsmith wrote: ↑Sat Nov 27, 2021 11:43 pm If people don't like learning the order of operations, we could always go to Reverse Polish Notation (or Postfix): 2+2x3 becomes 2 2 3 x +. Never any confusion.

Buddies of mine in high school and college had HP Scientific Calculators, and they used RPN. Not having one, I never got the hang of them...