maths!!

[Cookaburra]

why does
2(6x2.5)
give a different answer from
12x5
???

please help it is driving me crazy!!

[rojash]

2(6x2.5) doesn't mean mulitply 6 by 2 and 2.5 by 2!
It means First multiply (6 by 2.5 ) THEN multiply the result by 2.
6 x 2.5=15
2 x 15 = 30

In other words 12 x 2.5 NOT 12 x 5

[Cookaburra]

but why does it matter which one you do!!

when 2(6x2.5) it should be the same answer shouldn't it!!
if you try it with other sums like
6(5x2.5)
30x15
whilst writing that down i realised it was wrong!! but i don't understand why it is wrong??

[bloop-]

you have to follow
B.E.M.D.A.S

Brackets
Exponants(square,square root..etc)
Multiplication
Division
Addition
Subtraction

if you dont do the sum in this order yu will end up gettin a wrong answer

[Cookaburra]

so does that mean i have to expand the brackets first and then do the multiplication??

[mibn2cweus]

The distributive property:
a * ( b + c ) = ( a * b ) + ( a * c)
does not apply when terms within parenthesis are to be multiplied together: a * ( b * c)

The associative property alone applies to both:
a + ( b + c) = ( a + b ) + c
and
a * ( b * c) = ( a * b ) * c

associative and distributive properties explained here

[Whickerman]

let's make this simple. When there are brackets - do that part first. So that would be 6 x 2.5, ok?

Then multiply by 2.

In your second example, you say 6(5x2.5) is the same as 30 x 15. It's not, it's the same as 30 x 2.5, as you've in effect 'used up' the 6.

If, on the other hand, the brackets had a plus or minus instead of multiplied by or divided by, then it would work out as you first thought, ie 10(3+4) is the same as 30 + 40.

[newtron]

mibn2cweus is correct. In the example above :
2*(6*2.5) = 6*(2*2.5) = 2.5*(2*6) according to the associative property. Cookaburra thought that the distributive property applied, but it only applies when the terms in parenthesis are being added or subtracted..

[chakka35]

mibn2, you were just showing off there. Not like you.

[naomi24]

Chakka, quite right - not like mib at all, is it mib? :o)

[kwicky]

The brackets are redundant:

ie 2 x 6 x 2.5

[mibn2cweus]

₪ασмī ąņď �ħдККд,�����╔ײַ╗ №�!

[mibn2cweus]

╔ײַ╗?

[naomi24]

mib, chakka's obviously not going to ask, so I will. What?

[mibn2cweus]

See what you made me do? lol

Apparently I ran across a bug in the way characters as they were presented in the preview are finally displayed following submittion. Quarks like that invariably turn up when I am doing my very best to truly show off.

Now that Cookaburra has probably been pushed over the edge, our work here is done. Let's all move on then; shall we?

C�> ����������<�?
~~~╚Ω╝~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ <o/�\o>

[naomi24]

Good idea, mib. :o)