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Author Topic: 2 + 2 x 2 = ?  (Read 8152 times)
6 OF 2 redundant adjunct of unimatrix 01
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« on: May 03, 2011, 22:55:31 »

i remember a while ago i did a maths question.... what's the answer to this one?

2 + 2 x 2 = ?
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inspector_blakey
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« Reply #1 on: May 03, 2011, 22:57:48 »

The normal rules state that in the absence of any brackets, you do the multiplication first, then the addition. So the answer is 2x2, then add the other 2, for a total of 6.
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6 OF 2 redundant adjunct of unimatrix 01
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« Reply #2 on: May 03, 2011, 22:59:10 »

if u explain it... it removes the chance of people replying with 8....  Grin ah well
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inspector_blakey
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« Reply #3 on: May 03, 2011, 23:01:01 »

What I don't know is if there's some logical mathematical reason for doing things that way, or if it's just the convention because there has to be some way of doing it that's arbitrarily defined as correct.
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6 OF 2 redundant adjunct of unimatrix 01
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« Reply #4 on: May 03, 2011, 23:06:08 »

i have to be honest i came up with 8... and i can give workings that are logical and it comes to 8 but apparently without brackets or a Vinculum order of operations has to apply .. this is actually going around facebook but i was interested to see how many if any would say 8  Embarrassed
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inspector_blakey
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« Reply #5 on: May 03, 2011, 23:09:15 »

You just made me have to go and look up the word "vinculum" though Wink
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Chris from Nailsea
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« Reply #6 on: May 03, 2011, 23:17:52 »

I'd agree with blakey - see http://www.mathsisfun.com/operation-order-bodmas.html  Wink Cheesy Grin
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6 OF 2 redundant adjunct of unimatrix 01
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« Reply #7 on: May 03, 2011, 23:20:39 »

apparent answer from mensa ... apparently it is some random on facebook that emailed them
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It's not a puzzle we have set so can't really say what was intended. We presume the different answers that you can make are 8 or 6. If one was to apply the order of operations - that multiplication comes before addition. Probably the best interpretation is 2+(2x2) =? Making the answer 8. Some of course will argue the other way.

Sorry if that doesn't help
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inspector_blakey
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« Reply #8 on: May 03, 2011, 23:26:44 »

I'm slightly dubious about the apparent answer from Mensa given that they apparently can't evaluate 2 + (2 x 2) correctly!!
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Chris from Nailsea
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« Reply #9 on: May 03, 2011, 23:30:12 »

Again, I agree with blakey!  Roll Eyes
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William Huskisson MP (Member of Parliament) was the first person to be killed by a train while crossing the tracks, in 1830.  Many more have died in the same way since then.  Don't take a chance: stop, look, listen.

"Level crossings are safe, unless they are used in an unsafe manner."  Discuss.
6 OF 2 redundant adjunct of unimatrix 01
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« Reply #10 on: May 03, 2011, 23:34:36 »

haha  Grin

gotta love facebook
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devon_metro
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« Reply #11 on: May 04, 2011, 00:05:54 »

Another one doing the rounds on facebook...

Q: 6^2(1+2)

A: 1
or
A: 9

Over to everybody else...
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inspector_blakey
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« Reply #12 on: May 04, 2011, 01:52:22 »

Sort out the bracket first, so you get 6 / 2 x 3.

Precedence between multiplication and division is equal so I guess you just work through sequentially to get 9. Although I'm ready to be corrected.
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devon_metro
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« Reply #13 on: May 04, 2011, 02:12:45 »

Interesting actually, the way you state it makes perfect sence for it to be 9 too. I had initially worked it out as 1.

6 / 2(3)

6/6 = 1

The thing with getting 9 is the fact that you get 9 if you ignore bidmas, i.e. divide, then brackets since: 6/2 x (1+2) => 3 x (1+2) => 3x3 = 9, and as you've broken the rules of bidmas it must be wrong (?)

You can't achieve the answer of 1 by fouling the rules as far as I can tell!
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devon_metro
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« Reply #14 on: May 04, 2011, 02:16:58 »

Just to be contraversial the mighty wolfram alpha works it out as ... 9!
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