stevie_b Posted November 11, 2011 Share Posted November 11, 2011 5+5+5-5+5+5-5+5x0 BODMAS says you should do the multiplication first 5+5+5-5+5+5-5+0 Then you should do the addition 15-15-5 but there is no convention to the order of subtractions. so the answer could be either 0-5 = -5 or 15-10 = 5 The answer is 15, you're right. You have an error in your line where you say 15-15-5. By doing that you've implied brackets around 3 of the fives: 5+5+5-5+5+5-5 does not equal 5+5+5-(5+5+5)-5 Quote Link to comment Share on other sites More sharing options...
Scott Posted November 11, 2011 Share Posted November 11, 2011 The syntax for the question still has me thinking there is more to it. The one's I have seen on FB aren't implied as "basic maths" problems. They are simply put forward as "what is the answer to". I realise that I may be over complicating it and looking for something that maybe isn't there but surely it can't be as simple as what it appears to be? Quote Link to comment Share on other sites More sharing options...
garethr Posted November 11, 2011 Share Posted November 11, 2011 If you type the expression into Google, it very helpfully adds brackets to avoid any confusion: http://www.google.co.uk/search?q=5%2B5%2B5-5%2B5%2B5-5%2B5+x+0&btnG=Search&oe=utf-8&client=firefox-a&rlz=1R1GGLL_en___GB396 Quote Link to comment Share on other sites More sharing options...
Digsy Posted November 11, 2011 Share Posted November 11, 2011 I never thought I'd ever come across an internet discussion about BODMAS. Its definately 15. My maths teacher would gave said so, Excel says so and Windows calculator (even in basic mode) says so. To remove any confusion over spaces and multiplication notation: a=5 b=0 so the equation becomes: a+a+a-a+a+a-a+a x b or, a+a+a-a+a+a-a+a . b or, if you prefer, getting rid of the "x" or middle dot entirely: a+a+a-a+a+a-a+a b In the last form its especially clear that "a b" is a seperate expression that you have to evaluate first before adding the result to the rest of the equation. Quote Link to comment Share on other sites More sharing options...
caseys Posted November 11, 2011 Author Share Posted November 11, 2011 I never thought I'd ever come across an internet discussion about BODMAS. Good isn't it? I thought this'd start some interesting healthy debate and it has And hooray, no-one's sworn at it yet. It does though highlight exactly the assumptions or the reliance on equipment that the people on FB are answering these questions with. This also stems from having a student who did a degree in 'I.T' who didn't know hexidecimal. It seems it's a Business IT degree - i.e. he could tell you what the term peripheral means, or maybe possibly what a bus is, but couldn't explain a working example. Bring back Computer Science... and people with an ability to do math. Quote Link to comment Share on other sites More sharing options...
boomstick Posted November 11, 2011 Share Posted November 11, 2011 Space is a neither a number nor a binary operator ... it never becomes part of an equation ... EOD ;-) Yep, its that simple! Formatting (with spaces that is) a formula/calculation has no effect whatsoever on the outcome of that calculation. Math has rules, you MUST use them... Spaces have nothing to do with math rules. Just like speedlimits... you have to obey the speedlimitssss... Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 11, 2011 Share Posted November 11, 2011 We had quants programmers arguing about this at work with java and APL people. Did the quants come up with 15 as the answer? This also stems from having a student who did a degree in 'I.T' who didn't know hexadecimal. That's pretty poor, but I guess it's a reflection of the "business" aspect superceding other things. Even nowadays, you can't go far in hands-on IT without at least understanding hex: RGB colours in HTML for example. Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted November 11, 2011 Share Posted November 11, 2011 This post seems strangely apt Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 11, 2011 Share Posted November 11, 2011 Its definately 15. ... Windows calculator (even in basic mode) says so. The Windows XP calculator in basic mode doesn't follow BODMAS; it just implements a left-to-right precedence. Perhaps the Vista/Win7 incarnation of it does. Quote Link to comment Share on other sites More sharing options...
straightsix Posted November 11, 2011 Share Posted November 11, 2011 I hate puzzles and riddles and all those things designed to confuse and frustrate. Way to start my day! Bah! Grump....mutter.....moan.... Quote Link to comment Share on other sites More sharing options...
Digsy Posted November 11, 2011 Share Posted November 11, 2011 The Windows XP calculator in basic mode doesn't follow BODMAS; it just implements a left-to-right precedence. Perhaps the Vista/Win7 incarnation of it does. I aplogise, I just double checked and you are quite correct (I'm on XP). How odd that they would deliberately make it behave incorrectly just because it isn't in "sceintific" mode! Quote Link to comment Share on other sites More sharing options...
caseys Posted November 11, 2011 Author Share Posted November 11, 2011 This post seems strangely apt I have this bad image now of about 50 odd programmers worldwide doing something furiously underneath the desk. They were even showing windows calc, Google, Excel, Java, APL, Smalltalk, KDB and a texas instruments scientific calculator to show workings. Then we got back to order of execution and notation. There have been many ways to interpret the question, deriving different answers - I'm honestly amazed it took as many posts as it did before the bickering... sorry debate started I was just sick of the people on FB stating - it's this ... cos I said so and being so fricking close-minded to any other methodology Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 11, 2011 Share Posted November 11, 2011 How odd that they would deliberately make it behave incorrectly just because it isn't in "sceintific" mode! MS are probably emulating real-life calculators. Basic desk ones don't usually follow BODMAS either, or at least they didn't when I was a nipper. Quote Link to comment Share on other sites More sharing options...
Digsy Posted November 11, 2011 Share Posted November 11, 2011 MS are probably emulating real-life calculators. Basic desk ones don't usually follow BODMAS either, or at least they didn't when I was a nipper. The calculator on my HTC HD2 does the same thing. 0 in basic mode, then turn the phone 90degrees to put it in scientific mode and you get 15. Quote Link to comment Share on other sites More sharing options...
Attero Posted November 11, 2011 Share Posted November 11, 2011 My HTC calculator returns 15 in both basic and scientific. Quote Link to comment Share on other sites More sharing options...
DodgyRog Posted November 11, 2011 Share Posted November 11, 2011 So you have a plane and a treadmill:sly: Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted November 11, 2011 Share Posted November 11, 2011 So you have a plane and a treadmill:sly: So many of the members are different now. I wonder if we should try that one again Quote Link to comment Share on other sites More sharing options...
caseys Posted November 11, 2011 Author Share Posted November 11, 2011 MS are probably emulating real-life calculators. Basic desk ones don't usually follow BODMAS either, or at least they didn't when I was a nipper. Could you do BODMAS on an abacus? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 11, 2011 Share Posted November 11, 2011 Could you do BODMAS on an abacus? What's one of those? You're showing your age caseys! Quote Link to comment Share on other sites More sharing options...
Scott Posted November 11, 2011 Share Posted November 11, 2011 So many of the members are different now. I wonder if we should try that one again I stuck it up on FB earlier, not a lot of interest yet. Quote Link to comment Share on other sites More sharing options...
Pixelfill Posted November 12, 2011 Share Posted November 12, 2011 I voted 15, but I was probably wrong! I don't know what the answer actually is, because it would depend on the order you carry out the subtractions. 5+5+5-5+5+5-5+5x0 BODMAS says you should do the multiplication first 5+5+5-5+5+5-5+0 Then you should do the addition 15-15-5 but there is no convention to the order of subtractions. so the answer could be either 0-5 = -5 or 15-10 = 5 Interesting - and I hate you for proving my inadequacies. Mike I don't see how the people quoting BODMAS as the rule are still coming up with 15 as the answer. Did they all stop after BODM? Thus proving my maths (and computing) teachers were right when they said you should use brackets to remove the ambiguity of what you intended. Mike Quote Link to comment Share on other sites More sharing options...
TTRickeh Posted November 12, 2011 Share Posted November 12, 2011 I don't see how the people quoting BODMAS as the rule are still coming up with 15 as the answer. Did they all stop after BODM? Thus proving my maths (and computing) teachers were right when they said you should use brackets to remove the ambiguity of what you intended. Mike I don't understand what you are saying. There are five +5's (25...) and two -5's (-10...). 25-10=15. It doesn't matter which order the addition or subtraction is done in here? Quote Link to comment Share on other sites More sharing options...
stevie_b Posted November 12, 2011 Share Posted November 12, 2011 Pixelfill, 5+5+5-5+5+5-5+5 x 0 BODMAS says you do the multiplication before the addition or subtraction. So the expression becomes: 5+5+5-5+5+5-5+(5 x 0) = 5+5+5-5+5+5-5 It's then a case of applying the addition and subtraction left to right, keeping a running tally as you go: 5+5+5-5+5+5-5 Operation ........ Running total 5 .....................5 +5 ................. 10 +5 ................... 15 -5 .................... 10 +5 ................... 15 +5 .................. 20 -5 .................... 15 Hence the answer is 15 Quote Link to comment Share on other sites More sharing options...
Pixelfill Posted November 13, 2011 Share Posted November 13, 2011 Pixelfill, 5+5+5-5+5+5-5+5 x 0 BODMAS says you do the multiplication before the addition or subtraction. So the expression becomes: 5+5+5-5+5+5-5+(5 x 0) = 5+5+5-5+5+5-5 It's then a case of applying the addition and subtraction left to right, keeping a running tally as you go: 5+5+5-5+5+5-5 Operation ........ Running total 5 .....................5 +5 ................. 10 +5 ................... 15 -5 .................... 10 +5 ................... 15 +5 .................. 20 -5 .................... 15 Hence the answer is 15 I appreciate that, but applying the rules of BODMAS surely you shouldn't apply the addition and subtraction left to right, you should do the addition first and then the subtraction. to paraphrase you "BODMAS says you do the addition before the subtraction". So the expression becomes: (5+5+5)-(5+5+5)-5 15 - 15 - 5 running total = -5. surely you can't use the rules of BODMAS for part of the equation and not for the rest FWIW I thought it was 15 initially - now I'm not so sure Maths ... don't you just love it Mike Quote Link to comment Share on other sites More sharing options...
Pixelfill Posted November 13, 2011 Share Posted November 13, 2011 I appreciate that, but applying the rules of BODMAS surely you shouldn't apply the addition and subtraction left to right, you should do the addition first and then the subtraction. to paraphrase you "BODMAS says you do the addition before the subtraction". So the expression becomes: (5+5+5)-(5+5+5)-5 15 - 15 - 5 running total = -5. you can't use the rules of BODMAS for part of the equation and not for the rest FWIW I thought it was 15 initially - now I'm not so sure Maths ... don't you just love it Mike Right I'm happy now. The answer is DEFINITELY 15 ! It's BODMAS that is wrong, it should be BO(DM)(AS) http://www.mathsisfun.com/operation-order-bodmas.html Move along - nothing to see here. Mike Quote Link to comment Share on other sites More sharing options...
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