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Q&A #18836

Teachers' Lounge Discussion: PEMDAS problem

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From: Staal

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

Hi, 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, Staal

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