# Ordering Mathematical Operations | BODMAS

For a calculation that has only one mathematical operation with two numbers, it is a simple case of either adding, subtracting, multiplying or dividing to find your answer.

But what about when there are several numbers, and different operations? Maybe you need to divide and multiply, or add and divide. What do you do then?

Fortunately, mathematics is a logic-based discipline. As so often, there are some simple rules to follow that help you work out the order in which to do the calculation. These are known as the ‘Order of Operations’.

## Rules of Ordering in Mathematics - BODMAS BODMAS is a useful acronym that tells you the order in which you solve mathematical problems. It's important that you follow the rules of BODMAS, because without it your answers can be wrong.

The BODMAS acronym is for:

• Brackets (parts of a calculation inside brackets always come first).
• Orders (numbers involving powers or square roots).
• Division.
• Multiplication.
• Subtraction.

BODMAS, BIDMAS or PEMDAS?

You may often see BIDMAS instead of BODMAS. They are exactly the same. In BIDMAS, the ‘I’ refers to Indices, which are the same as Orders. For more information, see our page on Special Numbers and Concepts.

PEMDAS

PEMDAS is commonly used the in USA it works the same as BODMAS. The PEMDAS acronym is:

Parentheses,

Exponents (powers and roots),

Multiplication and Division,

Further Reading from Skills You Need

The Skills You Need Guide to Numeracy This four-part guide takes you through the basics of numeracy from arithmetic to algebra, with stops in between at fractions, decimals, geometry and statistics.

## Using BODMAS

### Brackets

#### Example:

4 × (3 + 2) = ?

You need to do the operation, inside the brackets first, 3 + 2, then multiply the answer by 4.

3 + 2 = 5.
4 × 5 = 20

If you ignored the brackets and did your calculation from left to right 4 × 3 + 2 you would get 14. You can see how the brackets make a difference to the answer.

### Orders

Do anything involving a power or a square root next (these are also known as orders), again working from left to right if there is more than one.

#### Example:

32 + 5 = ?

You need to calculate the power first, before you can add 5.

32 = 3 × 3 = 9
9 + 5 = 14

### Division and Multiplication

Once you have done any parts of the calculation involving brackets or powers the next step is division and multiplication.

Multiplication and division rank equally, so you work from left to right in the sum, doing each operation in the order in which it appears.

#### Example:

6 ÷ 2 + 7 × 4 = ?

You need to do division and multiplication first, but you have one of each.

Start from the left and work across to the right, which means that you start with 6 ÷ 2 = 3. Then do the multiplication, 7 × 4 = 28.

Your calculation is now 3 + 28.

See our pages: Multiplication and Division for more.

The final step is to calculate any addition or subtraction. Again, subtraction and addition rank equally, and you simply work from left to right.

#### Example:

4 + 6 − 7 + 3 = ?

You start on the left and work your way across.

4 + 6 = 10
10 − 7 = 3
3 + 3 = 6

See our pages: Addition and Subtraction for more.

### Bringing It All Together

This final worked example includes all elements of BODMAS.

#### Example:

4 + 82 × (30 ÷ 5) = ?

30 ÷ 5 = 6
This gives you 4 + 82 × 6 = ?

Then calculate the orders - in this case the square of 8.

82 = 64
Your calculation is now 4 + 64 × 6

Then move to the multiplication 64 × 6 = 384

Finally perform the addition. 4 + 384 = 388

## BODMAS Test Questions

The rules of BODMAS are easiest to understand with some practice and examples.

Try these calculations yourself and then open up the box (click on the + symbol to the left) to see the workings and answers.

### How Did You Do?

Hopefully you managed to get all the answers right. If not, go back and review where you went wrong, and read over the rules again.

The more you practise, the easier BODMAS becomes and eventually you won’t even have to think about it.

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