These questions drawn from dodgy internet question banks often create more confusion than understanding. They're better ignored; there's nothing you'll learn from studying the question in the post above that will help you in any way on your GMAT. For example, you will never, ever, see a 'vinculum' (horizontal bar) in place of parentheses on the GMAT, since almost no one would know what that meant. The GMAT will use parentheses instead. Nor will you see an expression which combines plain language ('of') with mathematical operations, as this question confusingly does. It is not at all clear how to group the numbers in the question above, so it's not surprising that people are arriving at different answers here. It's the question that's bad, not the answers given above.
Incidentally, in the acronym BEDMAS (and not BODMAS), which people sometimes learn to keep the order of mathematical operations straight, the 'E' stands for exponentiation; because we must perform exponentiation before multiplication, an expression like ax^2 always means (a)(x^2) and not (ax)^2. None of the letters in BEDMAS stand for the word 'of', as was suggested in a post above. It is true that the word 'of' normally indicates multiplication (as in the phrases '20% of 100' or '3/5 of 100'), but you will *never* see the word 'of' used in conjunction with other mathematical operations, since then the order of operations is unclear; none of the rules you will have learned explain what sequence to perform operations in when some operations are given in mathematical notation and some are given in plain English. That is, you will *never* see something like:
20% of 100 + 80
on the GMAT, since it isn't clear whether we should take 20% of 100 first, or add 80 to 100 first. If this were written in normal mathematical notation, then the meaning would be clear, so that's how the GMAT would write it.
That's a long post explaining why everyone here will be spending their time more productively by moving on as quickly as possible to more relevant practice questions. Where is this question from, by the way?
edit: I guess Stuart and I are both posting the same things at the same times!
Incidentally, in the acronym BEDMAS (and not BODMAS), which people sometimes learn to keep the order of mathematical operations straight, the 'E' stands for exponentiation; because we must perform exponentiation before multiplication, an expression like ax^2 always means (a)(x^2) and not (ax)^2. None of the letters in BEDMAS stand for the word 'of', as was suggested in a post above. It is true that the word 'of' normally indicates multiplication (as in the phrases '20% of 100' or '3/5 of 100'), but you will *never* see the word 'of' used in conjunction with other mathematical operations, since then the order of operations is unclear; none of the rules you will have learned explain what sequence to perform operations in when some operations are given in mathematical notation and some are given in plain English. That is, you will *never* see something like:
20% of 100 + 80
on the GMAT, since it isn't clear whether we should take 20% of 100 first, or add 80 to 100 first. If this were written in normal mathematical notation, then the meaning would be clear, so that's how the GMAT would write it.
That's a long post explaining why everyone here will be spending their time more productively by moving on as quickly as possible to more relevant practice questions. Where is this question from, by the way?
edit: I guess Stuart and I are both posting the same things at the same times!
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com
ianstewartgmat.com
ianstewartgmat.com
