" the acronym PEMDAS is common. It stands for Parentheses, Exponents, Multiplication/Division, Addition/Subtraction. PEMDAS is often expanded to the mnemonic "Please Excuse My Dear Aunt Sally"."
and
"These mnemonics may be misleading when written this way.For example, misinterpreting any of the above rules to mean "addition first, subtraction afterward" would incorrectly evaluate the expression
10 − 3 + 2.
The correct value is 9 (not 5, as would be the case if you added the 3 and the 2 before subtracting from the 10). " -- https://en.wikipedia.org/wiki/Order_of_operations#Mnemonics
Therefor the equation as written should be evaluated as (8/2)*(2+2) NOT 8+(2*(2+2)). Moreover, the equation should not be written in an ambiguous way.
This is like an optical illusion, for my Math OCD, completely unnerving.
That's the reason why you tend to work with fractions and horizontal bars, then you stick the parentheses into the numerator immediately. Fractions are a way to sort your product, without having to worry about the order. That the reason why PEMDAS isn't intuitive or all that useful. What you really do is look at the expression and see it it a sum is it a product. Not scan it left to right for what to do next.
I disagree.
ReplyDelete" the acronym PEMDAS is common. It stands for Parentheses, Exponents, Multiplication/Division, Addition/Subtraction. PEMDAS is often expanded to the mnemonic "Please Excuse My Dear Aunt Sally"."
and
"These mnemonics may be misleading when written this way.For example, misinterpreting any of the above rules to mean "addition first, subtraction afterward" would incorrectly evaluate the expression
10 − 3 + 2.
The correct value is 9 (not 5, as would be the case if you added the 3 and the 2 before subtracting from the 10). " -- https://en.wikipedia.org/wiki/Order_of_operations#Mnemonics
Therefor the equation as written should be evaluated as (8/2)*(2+2) NOT 8+(2*(2+2)). Moreover, the equation should not be written in an ambiguous way.
This is like an optical illusion, for my Math OCD, completely unnerving.
ReplyDeleteThat's the reason why you tend to work with fractions and horizontal bars, then you stick the parentheses into the numerator immediately. Fractions are a way to sort your product, without having to worry about the order. That the reason why PEMDAS isn't intuitive or all that useful. What you really do is look at the expression and see it it a sum is it a product. Not scan it left to right for what to do next.