What is 5-5x5+5?
- Thread starter Lysander
- Start date
I don't what to tell you, except that your education must have either been seriously lacking, or such a long time ago that you've forgotton! FWIW, I have a degree in maths, not that I need it for this level TBF!
How on earth do you get as far as A level maths without knowing that order of operations exists? It's something you're taught at KS3 (if not earlier?) these days.
Commissario
Brackets. Everything was bracketed which is surely a lot more straightforward than this. Work out the bracketed values and then do the rest because it removes all the ambiguities.
As per this.
Soldato
- Joined
- 18 Oct 2012
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- 8,333
so were you at least taught to add brackets around multiplications, divisions etc where none exist?
Evidently this was a counter-productive way to teach people then, as order of operations isn't some new fangled thing. Sounds like you were taught to bracket everything because they couldn't be bothered to teach you the proper rules.
In fairness, this entire question and many other varients like it, is mostly about trolling people like yourself! As you say, brackets make it far more obvious. I would say that there isn't any ambiguity - there isn't, there's one right answer and any other answer is definitively wrong, but if you actually want to communicate effectively to a large audience, then there is a certain responsibility on the person setting the question to make it obvious. This question is solely designed to trip people up, and going by this thread, it seems to have worked!
Soldato
5 But then I went to school in the 80's when we did proper maths. 
((5-5)x5)+5 = 5
((5-5)x5)+5 = 5
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Soldato
NO!
Permabanned
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No it's a Google Thread.
Commissario
No, it's a Facebook post.
Angus Higgins.
And @RxR is doing it wrong (since his sentence doesn't make sense [if using Higgins' bracketing system {as named by him}]).
5 But then I went to school in the 80's when we did proper maths.
((5-5)x5)+5 = 5
"The Internet - giving stupid people a voice since 1994."
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Because operations have different precedence, this has been true whether you learned some acronym like "BODMAS" at school or not.
Multiplication and division have higher precedence over addition and subtraction. These operators are right-associative too meaning you work from left to right...
So...
you have 5 * 5 which gives you 25 (multiplication ahead of addition and subtraction)
5 - 25 gives you -20 (working left to right)
and adding 5 gives you 15
Soldato
You don't need it for proper maths. It's intentionally ambiguous to provoke arguments on facebook and get post interaction level up.
Soldato
No, nothing like that. Just people not understanding bodmas. Its not weird or obscure and there's only one possible answer.
Commissario
There was no acronym, it was all about stuff being properly bracketed, as I’ve already explained. That way, anyone can follow it.