Q&A #18836

Teachers' Lounge Discussion: PEMDAS problem

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From: Staal

To: Teacher2Teacher Public Discussion
Date: 2008061317:08:04
Subject: Concerned


as to the resolution of whether 4/2*2 is 1 or 4 (a slight shortening
of the posed problem), one could say that
since / and * have equal precedence we adopt a convention of left
to right binding as the T2T reply suggested. Note that in the
realm of languages (say your calculator's) this is just a convention,
meaning that depending on which calculator you use, the answer 
can be either.

Another way to look at this is to go back to the mathematical context,
which I think can be taken to be operations in the usual real number
field. With this interpretation in mind, 4/2 becomes the
multiplication of 4 with the multiplicative inverse of 2 which we can
denote by 1/2. Then, 4/2*2 becomes 4 * 1/2 * 2 which resolves the
apparent ambiguity. 	

It seems to me that the question highlights the low value this society
places on giving its teachers the right tools and opportunities, and
by transitivity the value of educating its children.  

Best regards,

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