Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**glenberg****Member**- Registered: 2009-04-01
- Posts: 8

Hi is there any where I can look to practice the DOBMAS rule.

I'm doing the VETASSESS test and untill now I had never heard of this rule.

eg 2+3 X 7=21 not 35. how can maths change

Offline

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 22,042

2 + 3 x 7 = 23.

This is because, the order of operations is

Exponentiation (generally, this doesn't figue, so this can be overlooked),

Division, Multiplication, Addition, Subtraction.

Given the problem,

find the value of

The first operation to be done is division,

since 25 divided by 5 is 5,

the value is equal to

.

The next operation to be done is multiplication,

Since 2 x 3 = 6,

.

Mathematics or the operations on numbers don't change,

what changes is when to perform the operation, that is the order.

When brackets are used, the operations inside the brackets ought to be performed first.

for example,

.

It may be observed that the operations in the innermost brackets are performed first.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

Offline

**glenberg****Member**- Registered: 2009-04-01
- Posts: 8

Yes I know what your saying but my question in here can I find any practice like on this site mathsisfun there is long devision etc but nothing just to practice this BODMAS. maybe that should be included from simple sums to very hard sums

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,631

So you are saying we need plenty of "Order of Operations" exercises? Good idea.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**glenberg****Member**- Registered: 2009-04-01
- Posts: 8

do you know where I can find any Order of Operations exercises.

I need to pass a test very soon

Offline

**glenberg****Member**- Registered: 2009-04-01
- Posts: 8

ganesh wrote:

2 + 3 x 7 = 23.

This is because, the order of operations is

Exponentiation (generally, this doesn't figue, so this can be overlooked),

Division, Multiplication, Addition, Subtraction.

Given the problem,

find the value of

The first operation to be done is division,

since 25 divided by 5 is 5,

the value is equal to

.

The next operation to be done is multiplication,

Since 2 x 3 = 6,

.

Is the answer to this 6 or 4

*Last edited by glenberg (2009-04-01 22:59:36)*

Offline

**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,631

Have you read Order of Operations - BODMAS ... ?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

Offline

**sashaRR****Guest**

i need help with this one wat is (7+12)-(3x) i dont get my teacher does not do it good am in grade 6

**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 107,723

Hi sashaRR;

It you mean (7+12) - (3x) then always do what is inside of the parentheses first so

(7+12) is equal to 19 and (3x) is just 3x so your answer is

19 - 3x

Let me know if I have done what you needed.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.**** Always satisfy the Prime Directive of getting the right answer above all else.**

Offline