BIDMAS question - what's the right answer

[Overstating]

7-5+6x13?

Thanks!

whyami that's what I meant! There's generally only add and subtract left in those kind of questions and common sense dictates the order. Thank you!

Someone show me how they got -73

7-5+6x13

I’m trying to get -73 and am failing!

7-(5+6)x13 = 7-(11x13) = -136
(7-5+6)x13 = 8x13 = 104
7+(-5+6)x13 = 7+13 = 20

I clearly need coffee!

7-5+6x13

Ok going against the grain here and very ready to be told I am wrong..but I get -73. This is how I remember from school.
BODMAS
Brackets of Division, Multiplication, Addition, Subtraction.

So in this question:

Nothing in brackets.
No division.
So first, multiply 6 X 13 to get 65.
Then next addition. 5+65= 80.
Finally, subtraction. So 7-80 = -73

Please feel free to shout me down and tell me why I'm wrong though...

6x13 = 78

Except 6 X 13 is 78 not 65! Shame

And it's not 5 its -5 as the + and - stays with the number after it

So first, multiply 6 X 13 to get 65

This is incorrect. 6x13=78.

Your “addition” is incorrect as well. It would be -5 + 78 because the minus sign cannot be separated from the 5. -5 +78=73

Then you’re left with a 7 + 73 80.

Is BIDMAS the same as BODMAS? Where are the brackets? 80 is my answer

Oh god my mental arithmetic really is terrible. I did a level maths fgs

So its 78-5+7 = 80

Sort of wineymummy , except that 6x13=78 and I was so irritated by the duff maths that I failed to do the 'wrong' answer right and it should have been -76 .

But your logic is the one they used, that if addition comes next it's
5+78=83 and then the subtraction
7-83=-76.

But that removes the sign from the 5 - it should be
-5+78=73, then
7+73=80.

I've no clue what you lot are talking about

And everyone else is much more on it than me!

Trying again.

7-5+6x13

6x13 = 78.

5+78 = 83.

7-83 = -76.

I don't think it's relevant that the - stays with the 5. Otherwise 7-5 wouldn't make sense as a sum. BODMAS means subtraction is done last, so the end result is always going to be 7 minus whatever you get from 5+6x13. Which...I think (?!!??) is 83.

In my defence I'm pregnant and got some sh*t toddler telly on in the background and haven't done a sum in my head in about 20 years 😆

Shall we try it @teenplustwenties ?

slipperywhensparticus
If you’re old like me, you might have been taught this as orders of operations rather than seen the BODMAS/BIDMAS name for it.

And by 83...I mean 7-83. AARRGGHH

It is relevant as 7-5 means +7 (-5) which is 2. The + or - stays with the number

I would love the wine if it wasn't banned at the moment. 😬

I have never understood BIDMAS.
To me the logical way to do this is left to right, which gives you an answer of 104.
(7-5=2+6=8x13=104)

Can anyone explain when in real life you'd need BIDMAS over left to right calculations or is that a total derailing of the point of the thread?

Sorry winey you’re still wrong.

Does it help to see that 7 - 5 means 7 + -5?

And addition and subtraction are equal so can be done in any order.

But it doesn't pixie because the whole point of BODMAS is that the other sum is done first. You ignore the minus sign until the very end.

Not going to get into a Mumsnet argument anyway but in my mind it makes sense and I don't think the teacher deserves a bashing. I only got as far as a level so obviously aren't the most highly qualified person here to comment but that's my thoughts.

Multiplying and dividing are done before addition/subtraction - it's just a maths law