Math Question that Stumped the Internet!

#OlympiadMathematics #OlympiadPreparation #CollegeEntranceExam

[shubhamojha]

1st method is correct and second is wrong .it creates confusion . Great problem . thankyou premath from corner of my heart. Keep coming with these kinds of questions

[fevengr]

I see this issue raised from time to time and it shows, that in spite of there being a rule about order of operations, there is still confusion (and if this confusion wasn’t still an issue, then why was this video posted today?) If I was doing a financial calculation involving large amounts of money, I would add any additional parentheses, brackets, etc. in order to eliminate any possibility of ambiguity. I’m old and don’t remember all the rules, but with enough added parentheses and brackets, I can get the correct solution every time. Adding a bracket here and there might not be considered to be very elegant but it’s a lot less expensive than a $3000 error.

[jayquirk]

This is ambiguity at its worst and while it would seem to be "logical", in practice it is not useful. Take instead the equation 98 / 7x . In this case, it is generally accepted that 7x is a term to be grouped together. No one looks at this and considers the problem to be 98/7*x or x*98/7; it is seen as 98/(7x). Implying multiplication with brackets implies that the terms inside and outside the bracket are to be grouped together. PEDMAS does not take this into account as PEDMAS never considered implicit multiplication. In any case, use explicit operations and don't leave your math as a practice in interpretation by the user.

[avgala]

the symbol ÷ is called obelus and everything after the obelus should considered as denominator.

[nyanpasurenge_]

The 7 is actualy a "patch" for the bracket so you need to solve the entire 7(6+1) before anything else. This is how programing and scientific math works.

[HappyFamilyOnline]

Very nice explanation👍
Thanks for sharing🌹

[StevenMRSenior]

I disagree. I take 7(7) as still brackets so would be 49. Giving final answer as 2. This is how I was taught 50 years ago at school.

[jarikosonen]

It may need check with the matlab or wolfram alpha.
But *&/ is going left to right and +&- as well.
4+2-3+5, 4*2/3*5 both is left to right (but addition&substraction also right to left same result).
4^2^(1/3)^5 seems to go left to right as well (in octave) and right to left (in Wolfram alpha).

[owlsmath]

Good problem! I say never use that division sign...EVER!

[viralsentertainment]

2 must be the correct answer as 7(7) should be considered as a single term
For example if you solve 6X÷2X in algebra will give 3 as answer not 3X^2

[givenfirstnamefamilyfirstn]

I wasn’t taught strict left to right, I was taught to use brackets to remove possible ambiguity.

[zinff]

If we do according to BODMAS,
98÷7(6+1) multiplying 7 to solve brackets
We get 98÷42+7 we do division first

This is my opinion btw

[TheoWerewolf]

Ok... when I was in school we were taught BOMDAS not BODMAS (I've literally never heard this version until just now) said "brackets / [order] of / multiplication / division / addition / subtraction".

It was repeated several times across several grades. The reason I remember it is because it was only recently I heard PEMDAS used (although it's functionally the same as BOMDAS). The fact that apparently different *schools* are teaching different versions of this suggests that no - NONE of these are "officially" correct. In fact, I saw another video by a different math tutor saying literally the opposite of what you just said.

In the end, I use the same order system the computer languages I program in for a living use regardless if it's "right" or not. If I use something different, people could DIE (not exaggerating here - I write software that controls blast explosions in mines...). Fortunately we check the results of all of our equations rather than relying on cute mnemonics of which everyone seems to have their own "official" version.

[emmanuelambulaibainda]

98÷7(6+1)
= 98÷7(7)
= 98÷49
= 2. This is the appropriate answer.
The 7 before the bracket should be operated together with the bracket.

[RealMesaMike]

It only stumps people who think that this is a legitimately formed expression.

It is, in fact, ambiguous.
That's why ISO-80000-2 states that you shouldn't write expressions like this.

It's a poorly formed expression and if you ran into something like this in real life you would do well to do some research (contact the person who wrote it, for example) to determine what was actually meant.

By the way, PEMDAS (BODMAS, etc) are not "rules."
PEMDAS is a mnemonic device to help you remember mathematical operator precedence (not "order of operations").

[SomeTechGuy]

The second one is wrong. You'd have to bracket 7x7 in order for it to be correct.

[JD_ALMIGHTY]

98 according to bodmas and 2 according to basic calculation

[JSSTyger]

It used to be that the old division symbol meant to divide everything to the left of the symbol by everything on the right. So the answer would have been 98/[7(6+1)] = 2

[SAMATOZ]

I pulled out my trust CASIO FX82AU PLUS II and typed in 98÷7(6+1) and it gave the answer, including the rewritten '98÷(7(6+1))' as 2. I would have normally considered this incorrect. I was taught that you do division and multiplication left to right.

[Mete_Han]

Here is a question explaining the importance of transaction priority.