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PEMDAS and BODMAS

Sorry if this has been mentioned before, but surely they wouldn't give the same answer? According to PEMDAS, multiplication comes before division and BODMAS states the other way.

So for 6÷2×5 6 \div 2 \times 5

Using PEMDAS gives us 0.6
Using BODMAS gives us 15

Any opinions on this?
Both.
Reply 2
Original post by InadequateJusticex


Any opinions on this?


Multiplication and division are the same operation and are, therefore, completed left to right

So the answer is 15
Reply 3
What's PEDMAS? Wow everything changes when you leave school :smile:

Oh I spelt it wrong. It's PEMDAS
(edited 11 years ago)
Original post by Cephalus
What's PEDMAS? Wow everything changes when you leave school :smile:


The american version of BODMAS :redface:
Reply 5
Original post by InadequateJusticex
Sorry if this has been mentioned before, but surely they wouldn't give the same answer? According to PEMDAS, multiplication comes before division and BODMAS states the other way.

So for 6÷2×5 6 \div 2 \times 5

Using PEMDAS gives us 0.6
Using BODMAS gives us 15

Any opinions on this?


Strictly speaking, this isn't resolved by BODMAS/PEMDAS. These rules give division and multiplication equal priority, and likewise addition and subtraction: after all, division is just multiplication by a fraction, and subtraction is just addition of a negative. So in this sense, BODMAS, BOMDAS, BODMSA and BOMDSA all give the same rule.

If you interpret 6÷2×56 \div 2 \times 5 to be just a sequence of operations to carry out then by default you should work from left to right, to obtain 15.

But in the strictest sense, this is ambiguous. There are 'hidden brackets', which make it either (6÷2)×5(6 \div 2) \times 5 or 6÷(2×5)6 \div (2 \times 5), the former giving 15 and the latter giving 0.6, and without further context it's impossible to say with confidence which it is. In order to disambiguate, brackets should be added, or the fraction should be written in vertical notation to give either 62×5\dfrac{6}{2} \times 5 or 62×5\dfrac{6}{2 \times 5}.
(edited 11 years ago)
Original post by InadequateJusticex
Sorry if this has been mentioned before, but surely they wouldn't give the same answer? According to PEMDAS, multiplication comes before division and BODMAS states the other way.

So for 6÷2×5 6 \div 2 \times 5

Using PEMDAS gives us 0.6
Using BODMAS gives us 15

Any opinions on this?


Multiplication & Division are equivalent so saying one comes before the other makes little sense. Why not reduce it down to a product? 6÷2×5=6×12×5=156 \div 2 \times 5=6 \times \dfrac{1}{2} \times 5=15
Reply 7
Original post by Lord of the Flies
Multiplication & Division are equivalent so saying one comes before the other makes little sense. Why not reduce it down to a product? 6÷2×5=6×12×5=156 \div 2 \times 5=6 \times \dfrac{1}{2} \times 5=15


The real issue is in deciding whether

(i): 6÷2×5=6×12×56 \div 2 \times 5 = 6 \times \dfrac{1}{2} \times 5

or

(ii): 6÷2×5=6×12×56 \div 2 \times 5 = 6 \times \dfrac{1}{2 \times 5}

I'd expect (i) is the most common, and certainly what you'd assume if you were doing a basic (say, pre-A-level) arithmetic without any context to it; but there's no universally accepted reason why the notation couldn't also refer to (ii).
Original post by nuodai
there's no universally accepted reason why the notation couldn't also refer to (ii).


Ah, I wasn't aware. I thought "separating" the operations and substituting with their equivalents made complete sense given the absence of brackets:

(+6)  (÷2)  (×5)=(+6)  (×1/2)  (×5) (+6)\;(\div 2)\;(\times 5)=(+6)\;(\times 1/2)\;(\times 5)

Strange that there is still no universally accepted method for these things!
(edited 11 years ago)
Original post by Lord of the Flies
Ah, I wasn't aware. I thought "separating" the operations and substituting with their equivalents made complete sense given the absence of brackets:

(+6)  (÷2)  (×5)=(+6)  (×1/2)  (×5) (+6)\;(\div 2)\;(\times 5)=(+6)\;(\times 1/2)\;(\times 5)

Strange that there is still no universally accepted method for these things!


Mhm, there's a facebook question homogeneous to this, and in fact, it's both. Maybe they'll eventually overhaul the problem by just stating that in these scenarios a "left-to-right" approach is the more suitable. :smile:
Well actually, i am quite surprised no one gave this simple answer, but the matter of fact is, both agree same....if you see BODMAS, it does give priority to multiplication first, Cause BODMAS is Brackets Of Division Multiplication Addition and Subtraction, where 'Of' is nothing but multiplication.....
Reply 11
Original post by zaid_khxz
Well actually, i am quite surprised no one gave this simple answer, but the matter of fact is, both agree same....if you see BODMAS, it does give priority to multiplication first, Cause BODMAS is Brackets Of Division Multiplication Addition and Subtraction, where 'Of' is nothing but multiplication.....

This is incorrect. It doesn't matter which acronym you use, multiplation and division have equal priority.

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