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### Topic: 48÷2(9+3) = ? (Read 16773 times)previous topic - next topic

#### biocow

##### Apr 14, 2011, 06:37 pm
I've seen this on 2 different forums and it seems about 50/50 that people get it right. And hilariously the people who don't are adamant they are right. Let's see what happens here.

#### pluggy

#1
##### Apr 14, 2011, 06:49 pm
288 or 2 depending on how you look at it. It would need some extra brackets to be unambiguous I think.

http://pluggy.is-a-geek.com/index.html

#2
I'm going with 2

#### biocow

#3
##### Apr 14, 2011, 08:02 pm

...depending on how you look at it.

It's math. There can only be 1 answer.

#### AWOL

#4
##### Apr 14, 2011, 08:06 pm
It's an obvious inequality
'?' = 63
"Pete, it's a fool (who) looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

#### liuzengqiang

#5
##### Apr 14, 2011, 08:36 pm
288 makes more sense to me. I know why some answers 2 (obviously different order of calculation) but I can't think of a reason for 63. Your turn AWOL.

#### udoklein

#6
##### Apr 14, 2011, 08:45 pm
\begin{smartass}
You might expect 288. However you neither told the base for the number representation, nor the underlying field or ring in which to do the calculation. Assuming decimal representation and computations in Z you get 288. Hexadecimal in Z you get 1B0. Decimal representation computing in GF2 you have a division by 0. So you can get almost anything you want if you tweak the ring and/or the representation accordingly.

And you think 50% of the people get this right? I am impressed
\end{smartass}

#### udoklein

#7
##### Apr 14, 2011, 08:54 pm
@liudr: AWOL assumes ? == '?' because '?' == 63. So what he says is 48÷2(9+3) = ? is wrong and 48÷2(9+3) != ? would be right.

#### liuzengqiang

#8
##### Apr 14, 2011, 08:55 pm
I think you're smart. On the other hand, I didn't say my 288 was decimal. I could have different base on each digit, and fractional or irrational base to make 288 equal a lot of things.

#### udoklein

#9
##### Apr 14, 2011, 08:57 pm
Depending on the base and/or ring. That's what I said. But the OP said 50% of the people get this right...

#### udoklein

#10
##### Apr 14, 2011, 09:01 pm
Why not switch to Z/1Z and make your 288 equal to "anything"

#### liuzengqiang

#11
##### Apr 14, 2011, 10:04 pm
Yeah! In one of the recent exams I gave, I mentioned one senior professor in my department claims to be 35, base n years old and had my student estimate his base. ]

#### AWOL

#12
##### Apr 14, 2011, 10:08 pm
On second thoughts, '?' could also be 111
"Pete, it's a fool (who) looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

#13
:|