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Title: 2 + 2 x 2 = ? Post by: 6 OF 2 redundant adjunct of unimatrix 01 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 = ? Title: Re: 2 + 2 x 2 = ? Post by: inspector_blakey 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.
Title: Re: 2 + 2 x 2 = ? Post by: 6 OF 2 redundant adjunct of unimatrix 01 on May 03, 2011, 22:59:10 if u explain it... it removes the chance of people replying with 8.... ;D ah well
Title: Re: 2 + 2 x 2 = ? Post by: inspector_blakey 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.
Title: Re: 2 + 2 x 2 = ? Post by: 6 OF 2 redundant adjunct of unimatrix 01 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 :-[
Title: Re: 2 + 2 x 2 = ? Post by: inspector_blakey on May 03, 2011, 23:09:15 You just made me have to go and look up the word "vinculum" though ;)
Title: Re: 2 + 2 x 2 = ? Post by: Chris from Nailsea on May 03, 2011, 23:17:52 I'd agree with blakey - see http://www.mathsisfun.com/operation-order-bodmas.html ;) :D ;D
Title: Re: 2 + 2 x 2 = ? Post by: 6 OF 2 redundant adjunct of unimatrix 01 on May 03, 2011, 23:20:39 apparent answer from mensa ... apparently it is some random on facebook that emailed them
Quote 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 Title: Re: 2 + 2 x 2 = ? Post by: inspector_blakey 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!!
Title: Re: 2 + 2 x 2 = ? Post by: Chris from Nailsea on May 03, 2011, 23:30:12 Again, I agree with blakey! ::)
Title: Re: 2 + 2 x 2 = ? Post by: 6 OF 2 redundant adjunct of unimatrix 01 on May 03, 2011, 23:34:36 haha ;D
gotta love facebook Title: Re: 2 + 2 x 2 = ? Post by: devon_metro 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... Title: Re: 2 + 2 x 2 = ? Post by: inspector_blakey 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. Title: Re: 2 + 2 x 2 = ? Post by: devon_metro 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! Title: Re: 2 + 2 x 2 = ? Post by: devon_metro on May 04, 2011, 02:16:58 Just to be contraversial the mighty wolfram alpha works it out as ... 9!
Title: Re: 2 + 2 x 2 = ? Post by: 6 OF 2 redundant adjunct of unimatrix 01 on May 04, 2011, 02:50:30 I'm in too deep haha
Title: Re: 2 + 2 x 2 = ? Post by: LiskeardRich on May 04, 2011, 14:18:13 the way i was taught at school was BODMAS as rule of operations
B rackets O ??? cant remember but possibly pOwers D ivision M ultiplication A ddition S ubtraction so the 2+2x2 will be 6 the division question is 9 Title: Re: 2 + 2 x 2 = ? Post by: LiskeardRich on May 04, 2011, 14:21:24 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 (?) if you ignore bodmas/bidmas do the brackets, then mulitplication then division you get 1, correctly you'd do 6/2 followed by the answer x3 incorrectly you could do 2(3) =6 then 6/6 to get 1. You can't achieve the answer of 1 by fouling the rules as far as I can tell! Title: Re: 2 + 2 x 2 = ? Post by: Phil on May 04, 2011, 15:00:24 I get "hotel", but then I tend to always think in words rather than numbers.
Assuming B to be the 2nd letter of the alphabet, then... wait for it... A hotel equals twice a B&B Title: Re: 2 + 2 x 2 = ? Post by: paul7575 on May 04, 2011, 15:01:39 The O in 'BODMAS' was reckoned by one of my teachers to stand for 'Of' as in 'power Of'. Another reckoned it stood for 'Order' meaning powers or roots etc. I guess teachers get it explained differently as well... :o
Always made me wonder if 'O' was used just to make the initials more easily pronounced though. I do think 'I for indicies' is a better version... Paul Title: Re: 2 + 2 x 2 = ? Post by: Chris from Nailsea on May 04, 2011, 15:16:02 ... see http://www.mathsisfun.com/operation-order-bodmas.html ;) :D ;D There's a good explanation of 'bodmas' on that website ... ;) Title: Re: 2 + 2 x 2 = ? Post by: JayMac on May 04, 2011, 15:36:43 'BODMAS'
Is that not Bodmin Parkway to Manors (Tyne and Wear)? ;D Title: Re: 2 + 2 x 2 = ? Post by: Mookiemoo on May 04, 2011, 15:53:55 If you write it as
a + aa then its obvious which comes first Title: Re: 2 + 2 x 2 = ? Post by: eightf48544 on May 05, 2011, 07:55:41 I am sure I was was taught.
BOMDAS Brackets, Ofs, multiplication, division, addition, subtraction. With multiplication before division. So my answer to the second one is 1 Brackets (1+2)=3 Multiplication 2(3) = 6 Division 6/6 =1. BODMAS gives Brackets (1+2) = 3 Division 6/2(3) = 3/3 Division 3/3 = 1 There is a whole branch of mathematics based on these rules. Functions can be associative or cummulative (I've forgotten the exact rules) but it means something like that in certain functions the order of calculation does or doesn't matter. I've probably got a whole OU course unit on this in the loft. M100. Title: Re: 2 + 2 x 2 = ? Post by: grahame on May 05, 2011, 08:47:06 I always thought that the "O" was for Order - i.e. "raise to the power of".
Title: Re: 2 + 2 x 2 = ? Post by: LiskeardRich on May 05, 2011, 11:51:11 I am sure I was was taught. BOMDAS Brackets, Ofs, multiplication, division, addition, subtraction. With multiplication before division. So my answer to the second one is 1 Brackets (1+2)=3 Multiplication 2(3) = 6 Division 6/6 =1. BODMAS gives Brackets (1+2) = 3 Division 6/2(3) = 3/3 Division 3/3 = 1 There is a whole branch of mathematics based on these rules. Functions can be associative or cummulative (I've forgotten the exact rules) but it means something like that in certain functions the order of calculation does or doesn't matter. I've probably got a whole OU course unit on this in the loft. M100. your division of 3/3 was actually multip0lication in the original question 3x3 =9 Title: Re: 2 + 2 x 2 = ? Post by: inspector_blakey on May 05, 2011, 20:06:55 I am sure I was was taught. BOMDAS Brackets, Ofs, multiplication, division, addition, subtraction. With multiplication before division. So my answer to the second one is 1 Brackets (1+2)=3 Multiplication 2(3) = 6 Division 6/6 =1. BODMAS gives Brackets (1+2) = 3 Division 6/2(3) = 3/3 Division 3/3 = 1 There is a whole branch of mathematics based on these rules. Functions can be associative or cummulative (I've forgotten the exact rules) but it means something like that in certain functions the order of calculation does or doesn't matter. I've probably got a whole OU course unit on this in the loft. M100. And there you have the problem with BODMAS - it implies that division takes precedence over multiplication, with addition taking precedence over subtraction. In fact there is no such rule, with division/multiplication and addition/subtraction treated equally. Title: Re: 2 + 2 x 2 = ? Post by: TerminalJunkie on May 05, 2011, 23:16:51 A little experiment for MS Windows users: launch Calculator, and enter 1 + 2 * 3 =.
Make a mental note of the answer, then set it to 'Scientific View' and do the same calculation... Title: Re: 2 + 2 x 2 = ? Post by: Chris from Nailsea on May 06, 2011, 11:05:02 :o ::) ;D
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