BODMAS

Some people do need mnemonics, some don't.

Why does it need a mnemonic? It only complicates matters. I was no great shakes at maths but once explained the concept was so blindingly obvious, I didn't need to be reminded, it was programmed in.

So basically suesocks we both got the same answer but did it two different ways ...well that’s acceptable I couldn’t see how it was a 1.5 answer instead of 15 perhaps we re not so dim after all Joelsnan

SueSocks Red face! Believe it or not, it was my calculator that produced that result! I must have mistyped.

www.independent.co.uk/news/science/facebook-fruit-puzzle-answer-the-solution-to-the-simple-algebra-question-that-is-driving-social-a6879441.html

There is a catch which some people miss

Some puzzles on FB usually have bananas, coconuts or other objects in them.
People very rarely get the same answers

Joelsnan - correct!
Elegran - you started off correctly, but at the last stage 50 x 0.3 is 15 not 1.5.
These 2 methods both demonstrate correct use of BODMAS but what the mnemonic doesn't tell you is that you can change the order of Division & Multiplication
Eg think about 6 x 4 divided by 2
Division first gives 6 x 2 = 12
Multiplying first gives 24 divided by 2 = 12.
You must do all multiplying & dividing before you do + and -.
Same applies to + & -.
5+6-2 = 11-2=9
or
5+6-2 =5+4=9 if we do the subtracting first.

The name is just a mnemonic to remember it by.

I was taught this in the1950s, but it was never given a name, just taught as the order to solve equations.

It depends whether you read the sum as "Five lots of three plus four odd ones" or "Five lots of three plus four lots of three" Maths has to be exact. The order in which you do a process makes a difference. Imagine making a souffle omelette - you have to separate the eggs then beat the whites quite stiff before recombining the two parts. If you do the beating before the separating, you get a completely different result.

Words can be ambiguous, so an order of precedence means that everyone gets the same answer.
If you say "Five times four plus three" there are two ways to interpret it - the first is as "Multiply four by five, then add three" doing each bit in the order it is given.

The second is as "Five times what? Times four-plus-three." (which is seven) doing each bit in order of precedence.

I took GCE maths in the early 60s at grammar school and have never heard of BODMAS and how can two answer be right one must be wrong When I do those FB maths things I rarely get them as the younger people get one answer and the older folk get a different one
How could my answers be correct in 1960 but wrong in 2018
I would do the sum quoted by Joolsnan exactly the same as she has done and get the same answer but obviously that’s wrong and I can’t understand why at all

I remember BODMAS as well although I was never really clear about the "Of" bit. But I think (for what its worth) Elegran is right.

SueSocks I think the "Of" comes from predecimal calculations, where you might have to work out what "Half of 264 x (a third of 99 minus two-fifths of 350) plus a quarter of 1,760/73 " came to.

Heavens knows what the answer to that random sum might be, it probably ends up to a couple of dozen decimal places, but you would get there by doing the Brackets (which includes an couple of Ofs) then the other Of, then the / and the x and finally the +.

I am certainly doh!
I think I will give Facebook quizzes a miss from now on

50 x 3 / (6 + 4) would be

= 50 x 3 /10 (B for brackets first)
= 50 x 0.3 (D for division next)
= 1.5 ( Multiplying 50 by 0.3 gives you 1.5, not 150.)

If you want to do ALL that is outside the brackets before applying the / then you have to put another set of brackets around 50 x 3

50 x 3 / (6 + 4) would be

= 50 x 3/10 (B for brackets first)
= 50 x 0.3 (D for division next)
= 1.5 ( Multiplying 50 by 0.3 gives you 1.5, not 150.)

I was taught to do whatever was in the brackets first i.e.
50 x 3 / (6 + 4)
I would get 10 from the brackets then 150 from outside the bracket.
I would then divide 150 by 10 = 15
How would this be done using BODMAS ?

As an ex head of maths I would like to just back up the people who say it isn't new! I learnt it in the 70s and we still teach it today, although we tend to call it BIDMAS today, ie BRACKETS, INDICES, DIVISION, MULTIPLICATION, ADDITION AND SUBTRACTION.
Elegran explained it really well. We can't get 2 different answers to a sum like 5+3x4, which is why the rules of BIDMAS apply. Someone mentioned computers, well if you were to type this exact sum into a scientific calculator you would get 17, the correct answer, because the calculator has been built to recognise BIDMAS so it does the multiplying first to get 12 then adds the 5 to get 17. Many cheaper non-scientific calculators are not built to do this - creates a problem as you get the wrong answer!
At school I never understood what "Of" in Bodmas meant and it was never fully explained. Most people today use the word BIDMAS with the I meaning Indices which is basically squaring, cubing etc so you work out any brackets first, then do any indices after this you do your multiplying and dividing and finally any adding or subtracting.

But did you do it, even without the acronym? Did you work out what was in brackets before applying an operation to the contents of that bracket? For 6 x (5 + 3) would you make the answer 33 or 48?

Did you divide or multiply before adding or subtracting?

If you did either of these things, then you used the rule, even if you didn't know the acronym for remembering it.

I've never heard of it and got to A level maths without it.

And I remember slide rules!

I used BODMAS at school in the 60s. Nowadays they use BIDMAS according to DGS. The I stands for indices.

I remember Logarithms too. They were a way of working with very large numbers before the days of calculators.

ginny I was also at school during the 60s, I don't know how you never heard of BODMAS.

If the sum presented by elegran, 5 + 3 x 4, was presented as to a computer as written, the answer would be computed as 32 because it would be calculated from left to right, hence when coding the brackets have to be inserted (or the order changed) to get the right answer.

I didn't know it was called BODMAS either but do remember the mantra Brackets Off, Divide, Multiply, Add, Substract.

I loved maths at school and I come in handy for some maths home work. The thing I hated was Logarithms - what are they for?

All those problems we had to solve which left our brains scrambled - they were an attempt to have us thinking logically and deciding just what we had to do to all those numbers to work out the answer.