BODMAS I thought it was easy to use, now not so sure?!?!?!? Watch

ellishnoo
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#1
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#1
I thought Bodmas was easy. clearcut, now Im not so sure.

I was doing an online maths test when at the start they did a simple (I thought) Maths question...
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5-2+3x8=?

I think the answer is
3x8=24
2+24=26
5-26=-21

The program said I was wrong and I should do it as follows,
3x8=24
5-2=3
3+24=27

When I emailed them they said remember that in the bodmas rule the add and subtracts order didnt matter

Generaly I know this is true as
4-4+4=4 no mater which order one calculates this the answer is always 4

However when as in the first question, the order of the calculation of add and subtract result in two different answers, I thought you need to use the BODMAS rule in strict order.

Please can anyone give some feedback on this, as Im hung up on this seemingly easy process.
Cheers
Elli

Anyone have any thought on this
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ashy
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#2
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5 - 2 + (3x8) = 3 + 24 = 27

It's easiest if you just do all the multiplication together first. Then just do the addition/subtraction with the numbers you get from multiplication/division.
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dramaminedreams
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(5-2) + (3*8) = 3 + 24 = 27
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YoSuis
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BodMas just means that you di the multiplications/divisions before the additions/subtractions....after you've dealt with the multiplications/divisions you just go from left to right, you don't actually have to add first then subtract =] hope it helps
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ChosenOne
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(3x8)-2+5
5-2+(3x8)
-2+(3x8)+5

All the same and correct. Put brackets on the multiplication/division part and you shouldn't go wrong, that's all BODMAS is saying really: e.g. 5/9+2x7+6 --> (5/9)+(2x7)+6
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nuodai
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#6
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Really you should do it like (B)(O)(DM)(AS), since addition and subtraction are essentially the same thing (because a - b = a + (-b) and so on). That is, don't group addition and multiplication together (like you did).

Using brackets, if you have a - (b + c), this equates as a - b - c, for example.
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ellishnoo
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(Original post by ashy)
5 - 2 + (3x8) = 3 + 24 = 27

It's easiest if you just do all the multiplication together first. Then just do the addition/subtraction with the numbers you get from multiplication/division.
Many thanks for this, I was going a bit crazy looking for answers on the web, so the add and subtract are just calculated after, in order of appearance.
Cheers
Elli
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ellishnoo
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To all you relpliers, thank you so much for your time and speedy responses, now I totaly understand, and can finaly put this to bed and get onto the meaty stuff.

Cheers one and all.
Elli
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Trevor 12345
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It rather depends on how you see numbers as to how one approaches such questions. I tend to consider numbers as directed numbers and as a result if I am offered 4 -2 , what my brain actually sees is 4 + (-2).

thus if someone were to say consider 4 - 5 -3 + 2 and asked me to look at the 3; I would respond that there is no 3 in the expression, only a (-3).
I see the expression as 4 + (-5) + (-3) + 2
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c.e.stewart
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#10
Report 9 years ago
#10
The way you answered the equation is correct by my knolodge.Might be usefull to check this website though: http://www.scruffs.shetland.co.uk/files/Bodmas.htm
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