# Math Help - Rules of order helpplease

1. ## Rules of order helpplease

I have got an assignment headed "Rules of Order" in which there are a few thing I am not sure about, so this is what I have done.

Problem:- 15-12÷3X2=
I assume the rules of BIMDAS apply so I did this:- 15-12÷6=
Then 15-2= 13.

Next problem:- 50-5-10X2=
so I did this:- 50-5-20=
then:- 45-20=25

Am I on the right track here?

Thanks.

2. Hello,

Originally Posted by ptrott
I have got an assignment headed "Rules of Order" in which there are a few thing I am not sure about, so this is what I have done.

Problem:- 15-12÷3X2=
I assume the rules of BIMDAS apply so I did this:- 15-12÷6=
Then 15-2= 13.
It's 12÷3X2, not 12÷(3X2)

Hence divide first by 3, then multiply by 2.

Next problem:- 50-5-10X2=
so I did this:- 50-5-20=
then:- 45-20=25

Am I on the right track here?
It's incorrect ^^

-50-5 is not equal to -45 but to... ?

3. Originally Posted by Moo
Hello,

It's 12÷3X2, not 12÷(3X2)

Hence divide first by 3, then multiply by 2.

It's incorrect ^^

-50-5 is not equal to -45 but to... ?
Why is it 12÷3X2, not 12÷(3X2)??
Is there a different set of rules than Brackets, Indices, Multiply, Add, Subtract? If so, what are the correct rules for these problems?

Thanks.

4. Originally Posted by ptrott
Why is it 12÷3X2, not 12÷(3X2)??
Is there a different set of rules than Brackets, Indices, Multiply, Add, Subtract? If so, what are the correct rules for these problems?

Thanks.
What you did was dividing 12 by 6.
But this would mean that it was 12÷(3X2).

Whereas here, we have : 12÷3X2, which is the same as 12X2÷3

The order is (-, +) after (X, ÷)

Parenthesis are here to define other orders. For example in 12÷(3X2), it means that you do the multiplication first, so that you have 12÷6. But it's true if and only if there are parenthesis.

5. Thanks Moo, I'll go and try to get this into my head.

Cheers.