"Viral" maths problem

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Gavin Chipper
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"Viral" maths problem

Post by Gavin Chipper » Sun Nov 15, 2020 4:14 pm

I saw this come up on Facebook a day or so ago from The Mirror, so I thought I'd post it here. It's nothing original - I've seen similar before. It's also here.

What is 6 ÷ 2(1+2) ?

I'll be back to discuss.

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Re: "Viral" maths problem

Post by Johnny Canuck » Sun Nov 15, 2020 4:51 pm

Nine. Simple BEDMAS: do the bracket to get 6/2*3, then multiplication and division left to right. This is objectively the only answer.
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Matt Morrison
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Re: "Viral" maths problem

Post by Matt Morrison » Mon Nov 16, 2020 9:52 am

If a(b+c) == ab + ac isn't it 1?

Not done maths in many years so don't remember the rules as to when you would expand the brackets.

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Re: "Viral" maths problem

Post by Gavin Chipper » Mon Nov 16, 2020 12:45 pm

If you read the explanation in the second link I gave or watch this video, they're quite clear that the answer is 9.

However, I think to talk about it simply in terms of BEDMAS/BODMAS/BIDMAS/TISWAS is to miss the point about where the confusion or potential ambiguity lies. And the website and video do not address this.

We have 6 ÷ 2(1+2). If it was written as 6 ÷ 2 x (1+2) then pretty much everyone would agree that it is 9 and there would be no problem. The confusion comes from not putting the multiplication sign in leaving just 2(1+2) all stuck together because it looks like it is a term in the equation itself. Another example in the video is 1 ÷ 2y (even though as mentioned the video doesn't address the underlying source of confusion). Should that be taken as 1 / 2 * y, or 1 / (2y)?

The "correct" answer I suppose would just be whatever some committee of mathematical notation decides. It's not really a mathematical problem and talking of BEDMAS/BODMAS/BIDMAS/TISWAS does not resolve the problem either. But it is a poorly worded question and you'd never get anything written like that in "real life" outside a problem designed to deliberately confuse.

But aside fron the "correct" answer, we can still discuss what we think the aforementioned committee should reasonably decide. And I think if a number is put adjcent to the brackets like that with no multiplication sign then it's more reasonable to conclude that it goes with what's in the brackets so that they're treated as a single term. And that would make the answer 1. But because it's debatable and not everyone would agree, no-one should ever write a formula like that.

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Re: "Viral" maths problem

Post by Sam Cappleman-Lynes » Mon Nov 16, 2020 2:50 pm

Gavin Chipper wrote:
Mon Nov 16, 2020 12:45 pm
But because it's debatable and not everyone would agree, no-one should ever write a formula like that.
This is the only correct answer.

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Re: "Viral" maths problem

Post by Ian Fitzpatrick » Tue Nov 17, 2020 10:20 am

Sam Cappleman-Lynes wrote:
Mon Nov 16, 2020 2:50 pm
Gavin Chipper wrote:
Mon Nov 16, 2020 12:45 pm
But because it's debatable and not everyone would agree, no-one should ever write a formula like that.
This is the only correct answer.
Totally agree
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Re: "Viral" maths problem

Post by Tom S » Thu Nov 19, 2020 7:00 pm

1

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Re: "Viral" maths problem

Post by Johnny Canuck » Fri Nov 20, 2020 2:22 am

Matt Morrison wrote:
Mon Nov 16, 2020 9:52 am
==
Found a fellow programmer. Hello world.
Q: What is the longest word in the world?
A: "Gigaparsecs", because there is a gigaparsec before the last S.

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Matt Morrison
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Re: "Viral" maths problem

Post by Matt Morrison » Fri Nov 20, 2020 11:45 pm

Code: Select all

const printThisShitOut = `Gevin is in love with ${c4c.filter(c => !!c.cool).join(" and ")} and he is a prick.`;

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Re: "Viral" maths problem

Post by Fiona T » Sat Nov 21, 2020 12:10 am

Matt Morrison wrote:
Fri Nov 20, 2020 11:45 pm

Code: Select all

const printThisShitOut = `Gevin is in love with ${c4c.filter(c => !!c.cool).join(" and ")} and he is a prick.`;
Gevin's in love with himself ;)
8-) <-2m-> 8-)

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Re: "Viral" maths problem

Post by Gavin Chipper » Sat Nov 21, 2020 10:03 am

Someone has to be.

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Matt Morrison
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Re: "Viral" maths problem

Post by Matt Morrison » Sat Nov 21, 2020 1:24 pm

Damn I must've been drunk. Saw you quoting that and I thought I must've made that post years ago, not last night.

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Re: "Viral" maths problem

Post by Fiona T » Sat Nov 21, 2020 8:19 pm

Matt Morrison wrote:
Sat Nov 21, 2020 1:24 pm
Damn I must've been drunk. Saw you quoting that and I thought I must've made that post years ago, not last night.
Ha, me too - didn't notice the double not :D
8-) <-2m-> 8-)

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Re: "Viral" maths problem

Post by Matt Morrison » Sun Nov 22, 2020 10:46 am

I do like to work with booleans.

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