The BODMAS mathematical rule.

[XFool]

And Dod's last response is unreadable (to me at least) as a result of that.

Highlight it with the mouse.

Try that with both posts, at the same time, on a mobile.

Then just do what you people do on your smart phones. After all, they're 'Smart'.

[tjh290633]

The only way that I could read it on my mobile was to select "quote", read it then abandon the quote.

The problem with Dod's post is that he put it in the middle of the quote instead of after it. Hence at first glance there appeared to be no comment.

I am not a moderator on this board, so could not correct it.

TJH

[chas49]

And Dod's last response is unreadable (to me at least) as a result of that.

Highlight it with the mouse.

And just how does that help please?

I did that on modellingman's post. Dod has replied (also in colour), but without using quotes. I'm assuming that he did this unintentionally but it's not simple to distinguish his reply from the quote.

Actually this is partly also due to quoting the whole of the previous post.

I just don't think it's helpful to do this. (And as noted by PinkDalek it doesn't work too well on a mobile device.

[XFool]

And Dod's last response is unreadable (to me at least) as a result of that.

Highlight it with the mouse.

And just how does that help please?

Well you get to see it! Which is surely a start?

Presumably cutting and pasting to say, Notebook (in Windows), would render it in normal back type. I sometimes use Notebook for pre-editing or preparing a longish reply. Or you could edit out the colour tags in the TLF post editor, I assume. - Yes of course you can, just tried it.

Can't help with mobiles. Above my pay grade.

[PinkDalek]

Then just do what you people do on your smart phones. After all, they're 'Smart'. … Can't help with mobiles. Above my pay grade.

Can you help those who are colour blind and aren't able to copy into Word, Notebook or whatever?

Back on the PC, I can highlight modellingman's reply easily enough but not at the same time as Dod's reply.

To make it easier, for me at least, and look away now if easily offended, I'll copy and paste both replies below, such that I can see who wrote what.


SPOILER ALERT:

modellingman:

Its the 6/2*3 = 3/3 bit that is wrong.

6/2*3 = 3*3 if you follow BODMAS.

6/2*3 = 6/6 if you do not follow BODMAS rules, but instead do the multiplication before the division.

So a result of 9 under BODMAS and 1 if multiplication given priority over division.

Under BODMAS division and multiplication have equal precedence. And when two operators (a symbol such as *, /, + or -) have equal precedence in an expression the one that is used first is the one that is to the left of the other. So the division is undertaken before the multiplication in 6/2*3, but multiplication before division in, say, 6*2/3.


Dod (I've emboldened what I think are his comments):

Its the 6/2*3 = 3/3 bit that is wrong.

I do not see much wrong with my answer or logic. It is the / sign as I said later that is ambiguous and I will concede that either of the answers would be correct depending on how the / is interpreted.

Dod


6/2*3 = 3*3 if you follow BODMAS.

6/2*3 = 6/6 if you do not follow BODMAS rules, but instead do the multiplication before the division.

So a result of 9 under BODMAS and 1 if multiplication given priority over division.

Under BODMAS division and multiplication have equal precedence. And when two operators (a symbol such as *, /, + or -) have equal precedence in an expression the one that is used first is the one that is to the left of the other. So the division is undertaken before the multiplication in 6/2*3, but multiplication before division in, say, 6*2/3.

[melonfool]

Highlight it with the mouse.

And just how does that help please?

Well you get to see it! Which is surely a start?

Presumably cutting and pasting to say, Notebook (in Windows), would render it in normal back type. I sometimes use Notebook for pre-editing or preparing a longish reply. Or you could edit out the colour tags in the TLF post editor, I assume. - Yes of course you can, just tried it.

Can't help with mobiles. Above my pay grade.

I am bewildered as to why any post was posted in this way in the first place but I could see it by 'selecting' on the phone and then the words showed up - but when Dod posted I couldn't tell which bit he had posted and which was the original post as I couldn't scroll up again to look at (and highlight) the original post to compare I and I simply don't have the type of brain that can see and then recall equations.

But anyway, my understanding from listening to my ex stepson's maths tutoring, was that BODMAS is all school now and there's a new way to do it. I expect all will become clear after next September! (it won't....)

Mel

[GoSeigen]

Presumably cutting and pasting to say, Notebook (in Windows), would render it in normal back type.

By far the easiest is just to click the quote button at top right of the post, then read the quoted text in the message box.

GS

[XFool]

Presumably cutting and pasting to say, Notebook (in Windows), would render it in normal back type.

By far the easiest is just to click the quote button at top right of the post, then read the quoted text in the message box.

Yes. As I effectively went on to say in the above quoted post.

Presumably cutting and pasting to say, Notebook (in Windows), would render it in normal back type. I sometimes use Notebook for pre-editing or preparing a longish reply. Or you could edit out the colour tags in the TLF post editor, I assume. - Yes of course you can, just tried it.

[XFool]

But anyway, my understanding from listening to my ex stepson's maths tutoring, was that BODMAS is all school now and there's a new way to do it. I expect all will become clear after next September! (it won't....)l

BIDMAS? Which is the same as BODMAS. Just 'O' for 'Orders' updated to 'I' for 'Indices'.

[melonfool]

But anyway, my understanding from listening to my ex stepson's maths tutoring, was that BODMAS is all school now and there's a new way to do it. I expect all will become clear after next September! (it won't....)l

BIDMAS? Which is the same. Just 'O' for 'Orders' updated to 'I' for 'Indices'.

I wasn't listening *that* closely!

Mel

[modellingman]

I am losing the will to live a bit with this thread.

First, apologies to those who found my style of spoiler alert difficult to follow. I have no trouble selecting the text in posts either on a PC or an Android phone. However, that may be a function of the Chrome browser I am using. In this browser, selecting a light coloured text renders it white on a blue background. Readable by most I would guess. I did try and give a pointer through the instruction "select text to view". However, as requested, I'll avoid it on this board in future.

So onto the substantive issue (with colouring reverted to standard)

I do not see much wrong with my answer or logic. It is the / sign as I said later that is ambiguous and I will concede that either of the answers would be correct depending on how the / is interpreted.

The "answer" at issue is this

...but you could have done 6/2*(2+1) =6/2*3=3/3 =1 in strict accord with the BODMAS rules.

So, basically simplifying the elements of 6/2(2+1), one step at a time. No problems with that. It is done at every level of maths from pre-GCSE to post-PhD.

The step I pointed out in my "spoiler" as being in error is the one that goes from 6/2*3 to 3/3.

There are only two operators in 6/2*3, so all I was saying is that whichever order is used you get either 3*3 or 6/6 as the next step of simplification but never 3/3. Of course a pedant may argue that 3/3 is the same as 6/6, and you do get 6/6 if you don't follow BODMAS. However, 3/3 cannot be obtained from 6/3*2 without inserting an additional step or two, involving dividing numerator and bottom by 2. So spelling it out with brackets (for clarity) in the non-BODMAS case

6/3*2 = 6/(3*2) = (6/2)/((3*2)/2) = 3/((3*2)/2) = 3/(6/2) = 3/3.

Now, maybe that is what Dod101 intended. But only he can confirm this. And even if it is the full story of his logic it is, of course, not as has been asserted, in strict accordance with the BODMAS rules unless the heroic assumption is made that the "/" symbol is not shorthand for "÷" but instead signifies a divisor line with "6" in the numerator and "3*2" in the denominator. I can appreciate, but disagree with, this interpretation when the "/" symbol is surround by spaces but the expression Dod101 wrote (as the second post in this thread, so well before the arguments about divisor lines were introduced) contains no spaces at all.

I have my own theory of what lead to what I termed a "howler" on Dod101's part, but I'll keep that to myself for now at least.

[XFool]

Then just do what you people do on your smart phones. After all, they're 'Smart'. … Can't help with mobiles. Above my pay grade.

Can you help those who are colour blind and aren't able to copy into Word, Notebook or whatever?

If you are so colour blind that you cannot use TLF, then you would surely not be reading or posting here? If you are reading and posting on TLF, then you can't be THAT colour blind! And if anyway you cannot easily see the 'secret' text (like me) then you are no different to, well, me! Who, BTW, has in the past been diagnosed as... 'colour blind'!

I assumed using Windows, a well known OS, wrt the Notepad reference. Other operating systems and applications are available.

Back on the PC, I can highlight modellingman's reply easily enough but not at the same time as Dod's reply.

Why would you want to highlight two posts at the same time? Or do I misunderstand? (Again)

[melonfool]

Then just do what you people do on your smart phones. After all, they're 'Smart'. … Can't help with mobiles. Above my pay grade.

Can you help those who are colour blind and aren't able to copy into Word, Notebook or whatever?

If you are so colour blind that you cannot use TLF, then you would surely not be reading or posting here? If you are reading and posting on TLF, then you can't be THAT colour blind! And if anyway you cannot easily see the 'secret' text (like me) then you are no different to, well, me! Who, BTW, has in the past been diagnosed as... 'colour blind'!

I assumed using Windows, a well known OS, wrt the Notepad reference. Other operating systems and applications are available.

Back on the PC, I can highlight modellingman's reply easily enough but not at the same time as Dod's reply.

Why would you want to highlight two posts at the same time? Or do I misunderstand? (Again)

To compare them, as I said previously - the nuances of the odd / or *, or ( is too much to try to remember from one post to the next.

Mel

[XFool]

The step I pointed out in my "spoiler" as being in error is the one that goes from 6/2*3 to 3/3.

Yes. This was an obvious slip and Dod101 has already pointed it out in a preceding post. Though, as it was in 'secret' text, it appears to have blown up several Android phones - or some such. So may have been missed by some.

Its the 6/2*3 = 3/3 bit that is wrong.

I do not see much wrong with my answer or logic. It is the / sign as I said later that is ambiguous and I will concede that either of the answers would be correct depending on how the / is interpreted.

Dod

I have my own theory of what lead to what I termed a "howler" on Dod101's part, but I'll keep that to myself for now at least.

Oh go on.

[GoSeigen]

I have my own theory of what lead to what I termed a "howler" on Dod101's part, but I'll keep that to myself for now at least.

Oh go on.

I think it's obvious what Dod101 was saying, though of course he is the final arbiter. But my belief is that Dod interpreted the symbol / as representing the horizontal line in a fraction dividing the numerator and denominator. Thus everything on the left of that symbol was the numerator and everything to the right the denominator:

...but you could have done 6/2*(2+1) =6/2*3=3/3 =1 in strict accord with the BODMAS rules.

Then the 3/3 simply results from dividing by two in both the numerator and denominator.



As an aside, how would modellingman react to the following if seen in text-based forum:

y = 1/(x+1)(x-1)

or

x = (-b +/- SQR(b^2 - 4ac)) / 2a

Would the latter be "wrong" because the answer is a^2 times larger than it should be? I mean they are sloppy, but...


GS

[Dod101]

Yes GS that is how I interpreted the sign / and if I remember correctly so did many others. The simple answer is that the original question is to me ambiguous and so the 'correct' answer could be 1 or 9. Were it printed out on a question paper or written out it would be evident what the / was intended to cover.

Look I have a maths degree and this sort of basic arithmetic does not play a big part in that as anyone who has studied maths to A level never mind degree level will know. By that I mean that this sort of question does not in the scheme of things rate very highly. I would advise Mel if she is still reading to read the entire thread and then forget most of it, as it most likely will simply confuse her if she is looking to study GCSE in Maths.

I never learnt about BODMAS at school but then I hate mnemonics and could never see the point. Why not just learn the rule (because of course BODMAS is not the rule itself, just the mnemonic.

Dod

[modellingman]

As an aside, how would modellingman react to the following if seen in text-based forum:

y = 1/(x+1)(x-1)

or

x = (-b +/- SQR(b^2 - 4ac)) / 2a

Would the latter be "wrong" because the answer is a^2 times larger than it should be? I mean they are sloppy, but...


GS

Nice one!

Not trying to solve

(x/a)^2 + b*(x/a) + ac = 0

by any chance?

As an aside to an aside (an aside^2, perhaps), some forums do allow authors to write complex mathematical expressions with the full range of mathematical notation, including subscripts, superscripts, integral signs, greek letters, horizontal divider lines (so no need to guess an author's intention about the "/" symbol), etc using nothing more than a conventional keyboard or the soft keyboard of a smartphone. One such is https://math.stackexchange.com/, which uses LaTeX for input. The syntax takes a bit but not much learning. For a very short intro look here. The "block formula" example might look familiar.

[GoSeigen]

As an aside, how would modellingman react to the following if seen in text-based forum:

y = 1/(x+1)(x-1)

or

x = (-b +/- SQR(b^2 - 4ac)) / 2a

Would the latter be "wrong" because the answer is a^2 times larger than it should be? I mean they are sloppy, but...


GS

Nice one!

Not trying to solve

(x/a)^2 + b*(x/a) + ac = 0

by any chance?

GS

[scotia]

I confess that I had never heard of the BODMAS rule. But, as a (retired) engineer, I would give short shrift to any colleagues that chose to write a formula which could be interpreted in different ways - especially if a simple use of brackets would remove all dubiety.

[XFool]

I have my own theory of what lead to what I termed a "howler" on Dod101's part, but I'll keep that to myself for now at least.

Oh go on.

I think it's obvious what Dod101 was saying, though of course he is the final arbiter. But my belief is that Dod interpreted the symbol / as representing the horizontal line in a fraction dividing the numerator and denominator. Thus everything on the left of that symbol was the numerator and everything to the right the denominator:

Yes, yes. As did I and others.

But in this instance that isn't the "howler" modellingman was alluding to. Rather it was the obvious mistake, in the working out, of describing

6/2*3 = 3/3.

Which should instead have been(?) described as either: 3*3 = 9 or 6/6 = 1(?)

...

...but you could have done 6/2*(2+1) =6/2*3=3/3 =1 in strict accord with the BODMAS rules.

Then the 3/3 simply results from dividing by two in both the numerator and denominator.

Oh right!