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-   -   48÷2(9+3) = ??? (http://cellar.org/showthread.php?t=24914)

monster 04-14-2011 10:56 PM

Quote:

Originally Posted by Cloud (Post 723174)
logically, how can 48 divided by anything be 288? I still say 2

if you then multiply it by 12

Clodfobble 04-14-2011 11:02 PM

Quote:

Originally Posted by Undertoad
no i did the parens first and then, from left to right, division and then multiplication

You don't do multiplication/division from left-to-right like it's prose. Multiplication comes first regardless of where it is. Assume that the parentheses are done first, so now we have:

48 ÷ 2 x 12

That is the same as

48 x (one-half) x 12

Your way puts the 12 as a denominator in the fraction, which it wouldn't be unless there were also parentheses around the (2 x 12).


The mnemonic they taught us in grade school was My Dear Aunt Sally: multiplication, division, addition, then subtraction.

Undertoad 04-14-2011 11:05 PM

Multiplication AND division are done first...

monster 04-14-2011 11:05 PM

Quote:

Originally Posted by Undertoad (Post 723177)
it is written that way.

brackets first 9+3 = 12

then division 48/2 = 24

then multiplication 24 * 12 = 288

(a) No, it isn't written that way
(b) you're relying on Wikipedia

Undertoad 04-14-2011 11:09 PM

Google and Wolfram Alpha agree with me.

monster 04-14-2011 11:10 PM

Quote:

Originally Posted by Undertoad (Post 723182)
Multiplication AND division are done first...

there is no left to right in math. when there are both multiplication and division, multiplication goes first. that's why 2(whatever) means 2 * whatever. There is no division equivalent because it isn't needed because multiplication happens first

monster 04-14-2011 11:10 PM

Quote:

Originally Posted by Undertoad (Post 723184)
Google and Wolfram Alpha agree with me.

they're wrong.

Juniper 04-14-2011 11:12 PM

Order of operations: PEMDAS

Parentheses, equations, multiplication, division, addition, subtraction.

However, multiplication/division and addition/subtraction are equal.

Therefore, the answer is 24 x 12 = 288

Slinking back into the shadows now.

monster 04-14-2011 11:16 PM

Quote:

Originally Posted by Juniper (Post 723187)
Order of operations: multiplication, division,

However, multiplication/division and addition/subtraction are equal.

you are contradicting yourself. If they were equal, one wouldn't be before the other on the order of operations. Generally, there is no difference, but this is the illustration of why there is an order of ops that puts mult before div.

monster 04-14-2011 11:19 PM

At what point do I point out my BSc (honours) in math? I don't care what wikipedia says that google fetches up and other shit..... The answer is 2.

Undertoad 04-14-2011 11:21 PM

Yes but you got that degree off the back of a cereal box and I claim victory.

Juniper 04-14-2011 11:21 PM

PEMDAS is easier to say than PEDMSA but I guess you could do PEDMAS or BEDMAS (for brackets) and it wouldn't really matter. That's the way I was taught, back in the ice age.

Maybe I ought to ask my kids. I'm really not smarter than a 5th grader. :)

Or in my case, 7th grader and 9th grader . . . OMG, the 9th grader asked me for math homework help and I Could Not Do It. Algebra. Polynomials. :::scream:::

monster 04-14-2011 11:25 PM

Quote:

Originally Posted by Undertoad (Post 723190)
Yes but you got that degree off the back of a cereal box and I claim victory.

No, I didn't, and PEMDAS backs me up. Claim all the victory you like, you're still wrong.

Juniper, it does matter, that's why it's PEMDAS and nothing else. It just doesn't matter very often.

Math is not left to right -maybe that's why left-handers are good at it? :p:

skysidhe 04-14-2011 11:25 PM

288, just because I plugged it into my calculator as written.

Undertoad 04-14-2011 11:26 PM

Maybe my BSCS and three decades of computer programming will count for something?


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