There's a math problem raging on Facebook that depends on the order of operations.
Too many smart people have memorized the mnemonic BEDMAS and misapply it.
These mnemonics may be misleading when written this way, especially if the user is not aware that multiplication and division are of equal precedence, as are addition and subtraction. Using any of the above rules in the order "addition first, subtraction afterward" would also give the wrong answer to the problem:
.
The correct answer is 9 (and not 5, which we get when we do the addition first and then the subtraction). The best way to understand a combination of addition and subtraction is to think of the subtraction as addition of a negative number. In this case, we see the problem as the sum of positive ten, negative three, and positive two:
A different perspective that might help clear things up: Within the multiplication and division groups, start at the left and work right. Similarly, within the addition and subtraction groups, start at the left and work to the right.
But I doubt if this will stop or slow the battles on Facebook.
If only people would Google things and look at Wikipaedia...