UKH

Hi,

I'm after as many examples as I can find of different types of clickbait 'maths' problems.

The sort of thing i'm after are stuff like those below.  I'll post the answers in the next post, if people want to play along then don't read my reply.

How does 88888888=1000?

If 3*5=25
4*6=125
5*7=256
5*3=?


2+3=5
3+4=12
7+8=27
10+11=?


1223457=3
235677=2
133578=1
245678=4
133590=?


If you know of any others or a good place I can go to find a bunch of this sort of stuff then please let me know.

Many thanks for any help.

888+88+8+8+8=1000

if 3*5=25, then 5*3=25, the rest is irrelevant.  

2+3=5
(5)+3+4 = 12
(12)+7+8=27
(27)+10+11=48

the right hand side represents the number of even digits in the number to the left, so 133590=1

If you really don't like these puzzles, i'm with you.  I'm a maths teacher, they go against every grain of my education and to some extent my belief system, but there you go, so don't try and argue with me that these puzzles are rubbish, I entirely agree with you.

Most upsetting content on UKC for some time 

Yeah, I am sorry. I really am.

Pedant alert - that's a big jump - we don't actually know what your * operator means, it's obviously not normal multiplication so how can you possibly assume that it's commutative?

E.g. 3*5 means add 10 to both numbers, add them together and then subtract the first number = 25

But 5*3 with that operator = 23

That operator doesn't fit the other examples but you can see what I mean.

Yes, I know, I know, it’s all bloody nonsense. But, I’d really like as many of this type of nonsense as I can get my hands on. 

They're not complete rubbish, they're trying to make you look at things in different ways - after doing hundreds of these I bet your IQ test score would go up (not because it would make you more intelligent, I'd just make it easier to answer IQ type questions).

It's not maths, it's terminology and base.

Maths has no ambiguity, terminology does.

If you don't know what the * means, you don't know what the = means.  That's the point you pack up and go for a walk instead.

No, Michael is absolutely right.  These puzzles (when they're done correctly) have rules and they're more or less consistent.  Ok, maybe it's more of a convention than actual rules - like a crossword.  The = means =, but the other operators could be anything.

" if 3*5=25, then 5*3=25, the rest is irrelevant.  "

The OP may not like these puzzles but this is unfair, they're usually better than this.  You can't assume that the operation is commutative (because it clearly isn't just multiplication), and you can't leap to the conclusion that you know the answer without understanding what it's doing in the other two lines.  Besides, what kind of maths teacher sets a problem where it doesn't matter whether or not you understand the working as long as you drop on the 'right' answer?

When I read the thread title I assumed the OP was on about "maths" problems that are just a bit of slightly ambiguous arithmetic set up to get people arguing about BODMAS.  Now they really are garbage.

no, I don’t want them for the classroom, sorry for being vague. I want IQ type click bait nonsense. 
 

I’ve just realised from your reply that the biggest category of these type of puzzles involve ambiguous order of operations from the use of the division symbol. I’m more interested in unambiguous IQ puzzles than ones which are designed to cause an argument.

I realise I should have left out the 3*5 puzzle, that was always going to cause a row.

Yes, that’s my point.

The puzzle is not in the maths but in determining the rules.  If the rules are up for grabs, the meaning of every symbol is up for grabs.

Not necessarily, what if I said...

Define the * operator so that the following equations work and give the answer to the last equation

If 3*5=25
4*6=125
5*7=256
5*3=?

Then it becomes a more cogent problem - incidentally, has anyone worked it out - I fear it's beyond me.

They're not really puzzles at all (and as such they're more 'clickbaity' than the genuine unambiguous IQ type things).  They're just a bit of a wind-up, intended to generate engagement by getting people arguing about them in the comments.  As such I think your 3*5 puzzle belongs in the same category, even though it has nothing to do with the order of operations.

ok, I didn't intend to cause an argument here.  Perhaps I should have explained why I wanted them, but hay ho, I'll consider reposting with less controversial examples.

FWIW, i've found the original of the 3*5 question, I had misquoted it slightly, it was this.

If the below are true...

1=5
2=27
3=125
4=1880
What does 5=?

So it was probably less ambiguous than my example and we can all agree what = means, however it's clearly not an unambigous system of mathematics built on solid axioms.  It's a quiz show question.

This was from an episode of the ITV quiz show The 1% Club, so was verified as legitimate and unambiguous by an independent adjudicator.

Was it?  Unless I'm being extremely dim, it doesn't seem to bear any resemblance to it at all.

Yes it does. If 1=5, then 5=1; as he said the rest is irrelevant.

I read your OP and my blood was boiling. Fortunately scrolled on before responding.......

Yes, I'm puzzled too. It was the only one which looked like it might make any sense at all.

I mis-remembered the questions.  I thought that the question relied on an assumption that the * was commutative, and I wrote this.

If 3*5=25
4*6=125
5*7=256
5*3=?

The original question relied on the assumption that the = is symmetric

1=5
2=27
3=125
4=1880
What does 5=?

So, yes, they are different questions, but both rely on making an assumption about the system of logic being employed.

Sorry?

Oh, I see!  Yes, I was being dim then, thanks.  This version has different numbers and a different operator, but it's the same old bollocks.

In this case it's easier to demonstrate why - there's no need to talk about it being an unjustifiable assumption that the unknown operation is commutative, you can just rephrase the question like this:

Question: What is the fifth number in this sequence: 5, 27,125,1880,?
Answer: 1.  The first number is 5 so the fifth number must be 1.  The rest is irrelevant.

To look at it a different way, if the other numbers are irrelevant they could be anything right?  So how about this:

Question:
1=5
2=10
3=15
4=20
5=?

Answer:
1

This isn't a 'clickbaity maths problem', it's just garbage.

Yes, I agree, as I said upthread I know these are all junk we are in total agreement. 

You don’t by any chance have any other similar examples of such garbage do you?

‘Click bait’ something which causes engagement and often highly emotional responses on inane or incorrect material. I’ll just leave that there…

We're not in agreement.  The others aren't maths problems necessarily but they're 'lateral thinking' puzzles with a kind of consistent internal logic of their own.

This one is different, it's garbage in a way that the others aren't, so it's a category error to lump them all together.

Ok, sorry.

No need to apologise - I don't know if you think I'm making a 'highly emotional response' but I'm not cross or upset at all, just trying to point out how this particular puzzle is different to the others.  You could arguably call the others inane, but this is the only one that is incorrect.

There are lots of these things on Facebook written with appalling notation so you have to fully run through BODMAS for each operation.

Oddly enough, this just appeared on my twitter feed:

2 + 3 = 10
8 + 4 = 96
7 + 2 = 63
6 + 5 = 66
9 + 5 = ???

Somewhat more of a conventional puzzle than your examples but still an operator redefinition problem.

126

Wow, my brain still works 😁

put one line in this equation to make it true. 

101010=950

To me, these feel like murder mysteries. Suddenly a twin turns up and they were the murderer - with no clues to this eventuality. 

Thanks, that's the sort of thing i'm after.

Lovely, thanks, exactly the sort of nonsense I wanted to dig up.  

Sorry, I still have no idea what is going on. And deepsoup has only confused me further. Where did the * go?

How about putting the line through the = sign? 

The * shouldn't have been there in the first place.  I read a question a few weeks ago, which had been on the TV show, The 1% Club, I remembered it in my vague memory as "something to do with commutitivity which had 125 and a 5 in it and a lot of irrelevant information", and came up with the question I originally posted.

The question was actually about symmetry around the = sign, and that is what I then posted. 

So yes, they are different questions.

You are both right. I should have said 

make 101010 into 950 with one line.

I remember this one from uni (calculus):

x = y. 
Then x^2 = xy. 
Subtract the same thing from both sides: 
x^2 – y^2 = xy – y^2. 
Dividing by (x-y), obtain 
x + y = y. 
Since x = y, we see that 
2 y = y. 
Thus 2 = 1, since we started with y nonzero. 
Subtracting 1 from both sides, 
1 = 0.

Similar 

x = 0.999 recurring 

multiply both sides by 100

100x = 99.9999 recuring

subtract x from both sides

99x = 99

therefore 1=.9999 recurring 

Worth scouring Alex Bellos's Guardian column?

I had to look it up but it's a bit of a swindle because you need two dots as well as the stroke.

Yes, perhaps better as

Complete this statement

10 2 10 = 9 .......

Thanks, as a maths teacher one that almost every top set have shown me at some point and 'proved that 1=0' or similar.  Good to be reminded of it again!

In contrast to 1=0 this one is valid and correct!

42

Though you only need to multiply both sides by 10

Step 1 can be rewritten as 0=0. In step 2 you’re dividing this equation by 0, since x=y. So it doesn’t really make any sense.

(PS what is the answer to 0/0? Is it 0 or infinity?

There are hundreds of these bloody things in the GCHQ puzzle book. My son has been torturing me with it since his birthday.

I was given two copies of that book a few Christmases ago. After about half an hour trying one puzzle I looked up the answer and then shut the book in disgust and have never opened either again. Why would one waste time with this sort of stuff when one could be getting stuck into a proper maths problem? 

:-D I think that says more about you than it does about the book! My son loves it, but then his mind is very much shaped that way.

It's like the GCHQ Infinite Monkey Cage episode where Brian Cox set a puzzle for the listeners to try over the next week, answer to be announced in the next show, and a GCHQer in the audience shouted out the solution after a couple of seconds. A different species!

It's undefined.

Sometimes it's possible to surgically remove it from the range of an expression and replace with a "natural" value eg. sin(0) = 0 but the "sinc" function sin(x) / x converges to 1 as x approaches zero, so it's convenient to redefine sinc(0) = 1 instead of leaving it hanging. In other cases the "natural" answer might be zero or any other number or there might be no consistent replacement at all.

https://en.wikipedia.org/wiki/Removable_singularity

In the 1=0 "proof" the divide-by-zero happens for every value of x (not just 0) and is completely fatal.

no you don't ? where are the dots ?

One above the other after the 9. Unless you're aware of a different solution.

Just looked it up too. Glad I didn't waste more than ten seconds on it. Stupid problem.

Assume that we have two variables a and b, and that: a = b

Multiply both sides by a to get: a2 = ab

Subtract b2 from both sides to get: a2 – b2 = ab – b2

Factor the left side (using FOIL from algebra) to get (a + b)(a – b) and factor out b from the right side to get b(a – b). If you’re not sure how FOIL or factoring works, don’t worry—you can check that this all works by multiplying everything out to see that it matches. The end result is that our equation has become: (a + b)(a – b) = b(a – b)

Since (a – b) appears on both sides, we can cancel it to get: a + b = b

Since a = b (that’s the assumption we started with), we can substitute b in for a to get: b + b = b

Combining the two terms on the left gives us: 2b = b

Since b appears on both sides, we can divide through by b to get: 2 = 1

Discuss the assumed error.

Since multiplying by 0 appears on both sides, we can cancel it.

It's already been done, about half a dozen posts ago.

To be fair that was divide by zero, which is more obviously nonsensical. A carefully concealed multiply by zero I think is just a tad more subtle.

They look identical to me.

Its dividing both sides by a – b in the fifth step. But it's not dividing by zero—it’s dividing by a – b. As it's stated a is equal to b, meaning that a – b is the same thing as zero.

Yes, you're right. It was the word "cancel" that cloaked the fact that what he was doing was actually dividing.

Just as Ale152 divided both sides by x-y (where x=y) in the post you were replying to - it's the exact same thing.

Ah, ok 950 is the same as 9:50 surely  

Yeh I know it's annoying - but that's the point of the thread. When I saw the 'solution' I sighed too.