6 / 2(1+2) = 7

[mibn2cweus]

While the world argues over whether the correct answer is 1 or 9 . . . I get 7 as the answer.

So what's the problem with everyone else?

[jim360]

Independent of whether or not you consider this particular debate resolved, it is still a phenomenon that arguments can have been cleared up a long time ago and then someone rediscovers the wrong position and starts it up all over again.

What bothers me in particular about this one is that the people who insist that the answer is 1 either use flawed reasoning (eg Jackdaw repeating BODMAS all over the place, before proceeding to ignore it by multiplying first in preference to division, which would be BOMDAS; or Naomi's "my mathematician friend agrees with me", as if that's the only contribution to this thread by a qualified mathematician).

And I'm willing to bet that the other thing is that many of the people arguing in favour of 1 have little appreciation of the rules that might drive them to that answer, and it's based on distantly-remembered education.

Just by way of demonstration, let's rewrite the sum above as a / b(c+d) = x. Now, rearrange that equation to make d the subject. I expect that those people who insist on the answer being 1 would struggle to achieve this in a way that's self-consistent.

In the meantime, people like OG, ff, clover and I have a responsibility to at least try and make the case for the answer being 9; why even if you insist on its being 1 you have to accept that this relies on a peculiar and uncommon definition of the / operator (or on the idea of spacing as somehow carrying mathematical meaning); why, perhaps, the problem should be written out in a clearer way all the same; the importance of brackets; and just combating innumeracy wherever we see it.

[jim360]

In fact, thinking about it, why didn't I pose that problem earlier. It's impossible under the definition of / being used by those people who want the answer to be 1 without also violating the commutativity property of real numbers. Try it, and see.

[mibn2cweus]

You mean like this thread being commutated from R&S to Science?

[jim360]

Huh. Hadn't noticed that. Oh, well.

[fiction-factory]

What's green and commutes, jim?

[jim360]

Go on...

[mibn2cweus]

Pi R not squared. Cornbread R Squared. Pi R round.

[mibn2cweus]

. . . Naomi?

[Mamyalynne]

You can make square pies.

[Jackdaw33]

I defend my use of BODMAS. Brackets first. To remove brackets I was taught to multiply the contents by the number immediately to the left. You can thcream and thcream all you like, Jimbo, but the answer is ONE!!!

[fiction-factory]

An Abelian grape, jim

[fiction-factory]

The number immediately to the left could be 3/2 though Jackdaw

[fiction-factory]

I meant 6/2

[fiction-factory]

What's the volume of a cylindrical pizza of thickness z and radius a?

[Mamyalynne]

Pi(z*z)a

[bhg481]

B The value of the contents of the brackets is 1 + 2 = 3
O no content
D only divide there is 6/2 = 3
M 3 x contents of brackets = 3 x 3 = 9
A no addition other than in the brackets
S no subtraction.

Answer = 9

[Jackdaw33]

Pi a^2h

[mibn2cweus]

Jackdaw33
Mark as Best Answer
I defend my use of BODMAS. Brackets first. To remove brackets I was taught to multiply the contents by the number immediately to the left. You can thcream and thcream all you like, Jimbo, but the answer is ONE!!!
16:31 Thu 15th Sep 2016

Then the answer is . . . 7

6 / (2 X 1) + (2 X 2) = 6 / 2 + 4 = 3 + 4 = 7

[naomi24]

Jim, //What bothers me in particular about this one is ….Naomi's "my mathematician friend agrees with me", as if that's the only contribution to this thread by a qualified mathematician//

Tongue in cheek, Jim …. although he is extremely well qualified and he does agree with me. ;o)

Mibs, me ‘green’? Never! :o)

[mibn2cweus]

Ahem . . . Pi R not squared. Cornbread R Squared. Pi R round.