60÷5(7-5)
The "internet is arguing" about this sum.
What do you make the answer, without googling?
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130, but don't rely on me !
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BODMAS
Brackets, of, divide, multiply, add, subtract
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>> 130, but don't rely on me !
>>
New spectacles needed there Runfer? That's a divide sign not an addition sign!
:-)
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>New spectacles needed there Runfer? That's a divide sign not an addition sign!
Salesman maths. That's list price before your discount Sir.
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>> Salesman maths. That's list price before your discount Sir.
:-)))
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>> New spectacles needed there Runfer? That's a divide sign not an addition sign!
>>
>> :-)
Aye, well, there is that. Arms too short. :-(
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Left to right unless there is other precedence.
(7-5) = 2
60 ÷ 5 x 2
24
(or it might be 6)
Last edited by: No FM2R on Fri 12 Mar 21 at 15:05
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5(7-5) = a single sum = 5 x contents of brackets = 5 x 2 = 10.
60 / 10 = 6
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This is why, when I program (rarely) I always give an example of any calculation in the notes with real numbers and the steps taken to get there.
And I always code the long way.
EG
a = 7-5
b = 60/5
c = b x a
print c
Other programmers say I am not being efficient, but I can maintain may code fairly easily.
But as a rule, BODMAS
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>Other programmers say I am not being efficient, but I can maintain may code fairly easily.
If it's compiled rather than fully interpreted, the compiler will optimise the binary for you. Even some languages classed as interpreted eg Perl and Python are pre-compiled to byte code and optimised before they run.
Much better to write code that is readable and understandable than trying impress people with terse carp that is impossible to maintain.
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I was always taught OBMDAS (Oh bother my dear Aunt Sally) for precedence, but I believe BOMDAS is preferred nowadays.
Applying either gives 24.
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Ok - I didn't google it, but I just stuck it in a script... is that cheating?
$a = 60/5*(7-5);
Ans 24
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Well, now you've had a bash, here is "a mathematician" to tell you the answer. Or perhaps actually that's not the answer after all, depending. Or in fact it might not be actually answerable...
m.youtube.com/watch?v=wzchhbrqIBI
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>> Ok - I didn't google it, but I just stuck it in a script... is
>> that cheating?
>>
>> $a = 60/5*(7-5);
>>
>> Ans 24
>>
I could never do binary arithmetic. The theory wasn't the problem, it was the practice. Always making silly errors or couldn't read my own handwriting.
So one of my first programs on a ZX81 was to do binary arithmetic the long way, just to prove to my teacher that I knew what I was doing.
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Well, that's just stupid!
Or maybe I'm...
;-)
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I think the correct answer to this is that it is expressed ambiguously, and should be written more clearly, using more brackets.
That's a serious answer BTW, not a feeble try at a maths joke.
I thought the O in BODMAS stood for 'orders'?
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I got 6 - which is probably a sign of my age :-(
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I agree.. Not about your age!
Ii was taught to do it as
7-5 = 2
5 x 2 = 10
60 / 10 = 6
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It's a bit silly. Why would you be so ambiguous. Nobody would (should) write something so incompetently. It needs some more brackets either round (60÷5) or round (5(7-5)) to remove the ambiguity. But given we need to come up with an answer:
Clearly you do the bit in the brackets, the subtraction, first, and make 7-5=2.
Then you have 60 ÷ 5 x 2
And you work by convention from left to right, which gives you 24.
However, more pleasingly IMO is to regard 5(2) as making ten - much as in algebra you would like 5a, or 5b in a formula - which gives 60 ÷ 10 = 6.
Like many things that cause arguments, it's a bit silly.
Last edited by: Mapmaker on Fri 12 Mar 21 at 17:46
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>> Like many things that cause arguments, it's a bit silly.
>
Welcome back Mapmaker.
Yes, it's just a bit of fun, but it's all most interesting. Well, almost.
I always tended to think that maths was maths was maths, so if an ancient Greek wrote down a problem then the answer would be the same today, but now they tell me that in 1917 one answer to this one was right, but today another one is.
Unless, as you say, you just call it ambiguous anyway and no proper problem would be phrased that way.
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Cerise.
(I'm more arty than problem-solving).
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>>...... but now
>> they tell me that in 1917 one answer to this one was right, but today
>> another one is.
>>
...yeah, but I wasn't around in 1917 like some of you, which is why I gave the modern answer of 24. ;-)
(and is that 1917 according to the Gregorian calendar?)
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"...yeah, but I wasn't around in 1917 like some of you, which is why I gave the modern answer of 24. ;-)"
I blame my granddad - he told me.
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Four sand one cement. You've (almost) lost me:-)
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Hello Crankcase!
As a tax bod, ambiguity is my trade. I love ambiguity. But the important thing is to see two solutions, not one... If the internet is divided, then the entirety of the internet is wrong.
I do think 6 is the more pleasing solution - probably because I think you have to be a bit more clever/sneakier/better at lateral thinking to see it.
I've now watched your video, and whilst he obviously knows more about historical maths conventions than I do, I'm pleased he mostly agrees with me. Though I switched off long before the end; why use a three minute video for something that can be explained in a paragraph that can be read in seconds?
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I confess to being a poor mathematician, and I was thinking of something similar that a friend who's a science writer did a video on a while back. It's taken me a while to find it, and it is actually an identical problem with different numbers in. These things just resurface from time to time.
www.facebook.com/TheWorldsofDavidDarling/posts/2395774337183152
I think his attempt an an explanation is pretty good, I nearly understood it. I might have sent Crankcase's question to him but there seems little point.
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12.
I’ve no idea of the significance of the numbers in brackets.
At least I always have the right change for the bus driver, despite failing my Maths O level three times before giving up. Or being politely asked to stop wasting the examiners time.
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>>the significance of the numbers in brackets.
Just do the calculation in the brackets first is all it means.
The trouble starts after that when it's reduced to a division followed by a multiplication, and what order you do them in. It needs some more brackets to tell you which to do first, otherwise it's nonsense, unless you have an understanding of what the numbers represent.
I'm in the same cart as you really. I'm good enough at sums but poor at maths beyond a bit of basic algebra and geometry. The fact that I got a maths A level just gives me cause to be concerned at the common theory that things have been dumbed down! Fortunately my daughter is far better at maths than I am so I don't think that's necessarily so.
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If I saw that as an exam question...60 divided by 5 is 12. 7 minus 5, being the numbers in brackets, is 2.
So given that equation, if that is what it is, do you multiply/divide/subtract/add the 12 by 2. Or vice versa.
Just curious
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My mental maths is still ok. Always has been. Whilst shopping for grub I can add up 8 items in my brain box, say the total is £37.27. Give the cashier two twenties, plus £2.27 in shrapnel and expect a crisp fiver back.
Not rocket science. I can do that without even thinking about it.
My only understanding of logs (logarithms from skooldays) is something I put in my stove.
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Not have contactless in N Yorks ;-)
Bar buying something off gumtree, I can't remember the last time I used cash.
Oh yeah I got 24 as well.
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At school I was rubbish at maths. Soon after I got a Saturday job in a greengrocers (future f-i-l as it happened). We had scales for all the fruit and veg which simply weighed but you then had to work out the cost, in £sd, in your head and add it to the running total you kept in another part of your head, all the time being the cheerful chappie with the customer who were often out for a chat as much as anything. And the prices of stuff varied from week to week. I turned out to be quite good at that.
I think it's a skill you don't lose as I'm still pretty reasonable at manipulating figures in my head.
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During the War, Rodney.
When the London Blitz started, the school air raid shelters didn't have lights. To keep us occupied the teachers lead a sing-song, or got us to chant our 'times tables'. Once you have learnt your 'times tables' off by heart it never leaves you.
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>> Once you have learnt your 'times tables' off by heart it never leaves you.
My mum has dementia sufficient she doesn't really know you who I am, or indeed who she is. But ask her twelve nines and she can do it in a heartbeat. She also did the singing of multiplication tables. I guess that would have been the very early nineteen thirties.
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We had a 12 times table at the front of our classroom. Used to chant it every afternoon before going home time, followed by quick fire questions.
One of my abiding happy memories of Lilycroft infants school in Manningham, Bradford.
That and being read several pages of The Hobbit each day by Mr Frankland
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>> That and being read several pages of The Hobbit each day by Mr Frankland
Cool. We had Mr Poulton reading us The Phantom Tollbooth (surreal). More excitingly for us all, he drove an open Bentley speed six.
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My mate was a Poulton and his dad was a teacher, but in Essex and I don't recall a a Bentley.
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Well, this was, let's think, 1970/71, and I don't know what happened to him or the car after that...possible?
Last edited by: Crankcase on Sat 13 Mar 21 at 10:04
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In Essex though? They lived in Chingford, def from 1967 to 74
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>> In Essex though? They lived in Chingford, def from 1967 to 74
No then, this was Bedford. Oh well.
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>> My mate was a Poulton
What's one of those?
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I too have a maths A-level, but I'm not very good at it. How that came to be I can't imagine. (I have one in economics too as well as two more in English and physics. I'm not very good at any of those either. So much for the seventies exam system.)
I belong to a walking group (in normal times) and have palled up with a guy who turned to be an actual mathematician. He has no interest whatsoever in puzzles and the like, but whilst everyone else is talking politics and brexit, we wander along at the back while he tells me about the infinity of infinities or some such. I really like talking to experts, you learn so much you had no inkling of.
Decimal though - I can't help but turn "new" money back into shillings in my head, very easily for some reason. It does mean you keep falling over yourself mentally when you see a price and think a tiny chocolate bar is now eighteen shillings or some such, it sounds like such a huge amount when they used to be thruppence.
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Ha. I’m busy decluttering my life...selling lots of stuff on my local FB page...furniture, garage stuff gathering dust. Amazing what people will buy if it’s cheap enough.
They all pay cash...sometimes when buying stuff I offer them other stuff free of charge. Saves hoarding it until the charity shops reopen, when they will be inundated. I know because I help out at one.
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>> If I saw that as an exam question...60 divided by 5 is 12. 7 minus
>> 5, being the numbers in brackets, is 2.
>> So given that equation, if that is what it is, do you multiply/divide/subtract/add the 12
>> by 2. Or vice versa.
>> Just curious
It's not clear, is the right answer, because the expression is not "properly formed" and just doesn't tell you. But if I was forced to give a numerical answer it would be 24, using the slightly dodgy left-to-right presumption.
If you were to ignore the arbitrary left-to-right bit then I would take 5(7-5) = 5*2 = 10 as a 'sub-clause', divide it into 60, and come up with 6. Neither can be said to be wrong, hence it's ambiguous.
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I realise I didn't say what my initial instinctive answer was, which was six. I had trouble working out how the heck anyone got to twenty four before it was explained.
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I was the other way around, I got 24 and had to wait til someone explained how they got to 6 as I couldn't see how.
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BODMAS, and the answer is 6
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42.
Someone had to say it.
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Those who give the answer "24" seem to ignore that the 5 immediately adjacent the parentheses indicates that their content is to be multiplied by 5. It is not the same as writing 5 x (7 - 5), which is how a calculator would process the equation because it has not been better programmed. The multiplication by 5 thus comes under the "B" of BODMAS.
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60÷5(7-5)
6 is probably the best numerical answer. Because we have to guess at how best to interpret it (because BODMAS ranks division and multiplication equally) I'd tend to treat 5(7-5) as a group if I was guessing what is intended.
If it was written 60/5(7-5) I wouldn't feel that way. Using the ÷ suggests to me dividing by everything to the right of it.
I keep coming back to its being ambiguous. Even if there is a correct, conventional, way of calculating it, it is a damn silly thing to write if you know what you intend because it's easily clarified with another set of brackets.
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Maths problem - Runfer D'Hills
