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# Friday’s Math Puzzle

###### Posted by:Simona Prilogan

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16 replies to Friday’s Math Puzzle

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In your answer to Kate McClelland, above, you say that the multiplication is always performed first. Is that a relatively new rule? As I was taught, (decades ago), if the product of two or more factors is the active number, the factors are set off with parentheses, as in N-(16×0)=X. In that case, the answer would be 416, as you say. Without the parens, each number, N, 16 and 0, is distinct. Thus 416-16 x 0 has to equal 0.

Has my ancient brain forgotten something? Or is this doing the multiplication first perhaps a new rule?

Thank you for coming up with this question, cause it seems this kind of exercises are confusing sometimes. In our puzzle, we must definitely calculate firstly the multiplication, as we do not have any parentheses in the line. If we would have (N – 16)x 0, then we should do firstly the subtraction from parentheses.

“To eliminate this confusion, we have some rules of precedence, established at least as far back as the 1500s, called the “order of operations”. The “operations” are addition, subtraction, multiplication, division, exponentiation, and grouping; the “order” of these operations states which operations take precedence (are taken care of) before which other operations.

A common technique for remembering the order of operations is the abbreviation “PEMDAS”, which is turned into the phrase “Please Excuse My Dear Aunt Sally”. It stands for “Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction”. This tells you the ranks of the operations: Parentheses outrank exponents, which outrank multiplication and division (but multiplication and division are at the same rank), and these two outrank addition and subtraction (which are together on the bottom rank). When you have a bunch of operations of the same rank, you just operate from left to right. For instance, 15 Ã· 3 Ã— 4 is not 15 Ã· 12, but is rather 5 Ã— 4, because, going from left to right, you get to the division first….” (http://www.purplemath.com/modules/orderops.htm)

A

Yes! Have a great weekend! ðŸ™‚

Bonne fin de semaine Simona…bises

Merci beaucoup, Georges! Bonne fin de semaine a toi aussi. Bisous ðŸ™‚

416?

Da! Un weekend de exceptie! Calde imbratisari ðŸ™‚

C

No ðŸ˜¦ , because we must calculate firstly the multiplication then the subtraction.

Thank you for accepting the game.

Have a great weekend! ðŸ™‚

416?

Yes!

Have a great weekend! ðŸ™‚

A

Yes! Have a great weekend! ðŸ™‚

A) 416?

Daa! Un weekend de exceptie! ðŸ™‚