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 Post subject: At the risk of causing more BODMAS worry pleasePosted: Tue Sep 03, 2013 1:52 pm

Joined: Wed Feb 04, 2009 8:33 pm
Posts: 11
help as dh and I can't agree on these. Really grateful as trying to get head around this before having another go at explaining.
P.S. when did BODMAS get invented as Dh as A level maths and just says the questions all need brackets. Thanks so much

The Question asks student to indicate which of the following are correct

22-7 x = 45
makes no sense so wrong?

10 x 2 + 7 x 7 = 69
correct or is this 27 x7 ?

12 +3 x 7-3 = 30
Various possibilities
15 x 4 so wrong?
15 x 7 then minus 3 so wrong?
21 +12 -3 so correct?

30 ÷ 3 + 2 = 6
Wrong as anwer is 12?
Or right as is 30 divided by 5?

24 ÷ 4-3 x 2 = 0
Divide first so
6-3x2 is 3 x2 =6 so wrong
or multiply so correct as 6-6 is 0
or wrong as 6-3x2 =6

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 Post subject: Re: At the risk of causing more BODMAS worry pleasePosted: Tue Sep 03, 2013 1:59 pm

Joined: Mon May 16, 2011 1:05 pm
Posts: 3928
I was doing bodmas at school in the 80s, for O level.

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 Post subject: Re: At the risk of causing more BODMAS worry pleasePosted: Tue Sep 03, 2013 2:15 pm

Joined: Tue Oct 16, 2012 8:16 pm
Posts: 42
BODMAS was around when I did maths in the 80s.... You would only need to put brackets in if you wanted to process the numbers in a different way, ie to add/subtract sections BEFORE multiplying. Without brackets, BODMAS order apples.

I would say 2&3 are correct.

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 Post subject: Re: At the risk of causing more BODMAS worry pleasePosted: Tue Sep 03, 2013 5:55 pm

Joined: Mon Feb 12, 2007 1:21 pm
Posts: 11677
BODMAS is very old and was around when I was at school.

2 and 3 are correct and I think the last one.

24 ÷ 4-3 x 2 = 0

Divide

6 - 3 x 2

Multiply

6 - 6

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 Post subject: Re: At the risk of causing more BODMAS worry pleasePosted: Tue Sep 03, 2013 6:09 pm

Joined: Sat Jan 05, 2013 5:34 pm
Posts: 49
Hi,

22-7 x = 45
I think you are right, times what? It doesn't make sense. Odd question?

10 x 2 + 7 x 7 is the same as (10 x 2) + (7 x 7) since you have to do the multiplications before you add anything together. So you get 20 + 49 = 69. It's correct.

12 + 3 x 7 - 3 for this again the multiplication part has to be done first, so it's the same as 12 + (3 x 7) - 3 = 12 + 21 - 3 = 33 - 3 = 30 so again correct.

30 divided by 3 + 2 is the same as (30 divided by 3) + 2 = 10 + 2 = 12. Again, the division needs to be done ahead of the addition. So wrong (sorry my keyboard doesn't have the divided sign).

24 divided by 4 - 3 x 2 Again, the multiplication and the division have to be done ahead of the subtraction, so the maths sentence can be written as (24/4)-(3x2)=6-6=0. So this one is also correct.

The brackets aren't necessary to write an accurate maths sentence in each case, but it's normal to have the brackets written in to make it very clear.

It helps to use BIDMAS rather than the BODMAS we were taught in my school/university.
B brackets
I indices
D division
M multiplication
S subtraction

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 Post subject: Re: At the risk of causing more BODMAS worry pleasePosted: Tue Sep 03, 2013 6:56 pm

Joined: Tue Jul 21, 2009 9:56 pm
Posts: 8210

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 Post subject: Re: At the risk of causing more BODMAS worry pleasePosted: Wed Sep 04, 2013 7:57 am

Joined: Wed Feb 04, 2009 8:33 pm
Posts: 11
Thanks All. And, mystery, maybe being legless is the only way to stay sane !

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