6÷2(2+1)

Colleagues were in a heated argument over this one. 😋

BIDMAS.

@MammaNeedHummus They both agreed on that. And they still didn't agree on the answer 😋😋

Don't omit the multiplication sign and it should be fine.

Trying to Google why we have the BIDMAS order... So confused!
Why BIDMAS!!!!!!

There's no special order. Multiplication and division have the same order.

Unless you assign a special order for omitted multiplication there's nothing to argue about

@MammaNeedHummus bidmas is wrong though.

@iiii I need scientific papers for my drunk mind

Never really got the point of these. You could spend all day arguing about the technicalities of BODMAS, or you could just use appropriate brackets to avoid an argument and make it clear🤷‍♂️

That's because nobody actually uses the ÷ operator instead of a fraction unless they're deliberately trying to confuse people (or entering the equation into a simple calculator, I guess).

@EmberQuill exact argument for one of the colleagues who had 1 as an answer.

@MammaNeedHummus I mean that the acronym makes it confusing by assigning various order to multiplicative operations and to additive operations, while the order inside each of that group is identical.

And to be really nitpicky, in algebra there's no division but multiplication by a number with exponent -1, and no subtraction but addition of a negative number. 😄 So the acronym becomes simpler: BEMA - brackets, exponent, multiplication, addition

@PotatoCookie there's really no argument at all. Just depends on a preposition of whether implicit multiplication in an expression has a higher order than explicit one.

If it does have higher order, the answer is 1
If it does not, then the answer is 9

And the above-mentioned acronym helped jack shit, because it does not mention implicit multiplication in the order

@iiii I'll visualize my colleagues arguments in TeX, just a minute.

I'm confident the answer is 9, as I interpret the expression as:

6÷2(2+1)

6 divided by 2 times brackets 2 plus 1 close brackets

6 divided by 2 times 3

3 times 3

9

(New comment with "written" colleague argument in a minute, give me a moment 😋)

@iiii Here's his solution visualized.

His point basically was that "÷" is a written fraction and that ":" should be used if it is an "inline" fraction, and thus the solution is as in the graphical equation and not 9.

I don't know how I feel about that but he was adamant.

@PotatoCookie yup, he assumed that implicit multiplication has higher precedence

I would argue that a slash would be an "inline fraction" rather than that weird sign. But even then the brackets are mandatory as there is no common rule for such notation, unlike common rules for algebraic operations precedence (exponentiation, multiplication, addition) which save a huge ton if brackets of applied.

@iiii agree!

@PotatoCookie btw, I remember reading a manual for some Casio calculator which explicitly states that it indeed has a special order for implicit multiplication to save on brackets.

So that specific model will yield 1 with this expression

It's 42.

Any other answer requires an assumption to be made.

@C0D4 I don't know if I should laugh or ask you to elaborate 🤨

@PotatoCookie both 1 and 9 require an assumption to be made without supporting brackets.

So, 42 must be the answer.
https://en.wikipedia.org/wiki/...

@C0D4 Nice one! Went right over my head 😅

Was a good joke, my bad for not getting it on this one 😋

meh. trivial.

6÷2(2+1)

(* (÷ 6 2) (+ 2 1))

(* 3 3)

9

when in trouble, use the Lispy way of thinking. I live by that.

@kiki I agree with your solution however the answer 1 (scroll up a bit) is correct in some nuanced way, mainly a discussion on proper notation.

I haven't used Lisp yet. Or well yes I do for my spacemacs config but not in a really "use" way.

@PotatoCookie yeah that conventional elementary school math notation is outdated and sometimes confusing. Lisp-style notation eliminates the confusion entirely and makes things clear

@MammaNeedHummus @PotatoCookie BIDMAS is just another “five tomatoes” (five-two-eight-o) memo crap for imperial system. Those are random, outdated and confusing.

@kiki I'm not American so I don't use BIDMAS or the other acronyms however I understand their meaning and agree they are confusing and inadequate.

@C0D4 actually no.9 is without assumption, just using standard precedence rules.

@kiki prefix notation is not more or less superior to infix or postfix notation. They note the exact same expression but in different token order

@iiii assuming standard precedence apply 👀

@C0D4 standard is standard _because_ it is the default way without additional assumptions.

@C0D4 in the same way you could start arguing that every symbol does not mean what it means because it requires an assumption of standard Arabic numerical system and algebra

I love how this type of question always invokes the discussion around "What is the solution for the ambiguous problem?", while the more valuable question is: "How do we write the problem statement in a non-ambiguous way?".

@HerrNyani people do love polarisation 😋

I can't believe this topic got this many comments here

@electrineer ref. my comment above yours hehe

@kiki interestingly, that's almost exactly the opposite of reverse Polish notation (RPN) used especially in HP notation.

@iiii I prefer systems and notations that don’t need intricate manuals on how to use them

@kiki you don't need one for infix notation. And if you don't want to use precedence rules you can use brackets as well.

@electrineer because it's prefix notation while RPN is postfix notation

@electrineer HP calculators*

@iiii again, your assuming people made it past high school math and know the standards.

@C0D4 but it's middle school when it is taught

@iiii that's high school here 😅