Adding, Subtracting, Multiplying and Dividing are called operators. Operators perform actions on numbers.  

There are other operators, such as indices - these control operations such as squaring a number, or finding a square root.

Brackets ( ) are used to control the order in which calculations take place.

Each operation has a priority and control the sequence in which calculations are carried out:

• Brackets are always calculated first;

• Indices - such as 3² - are calculated next;

• Divide - is next;

• Multipy (actually has the same priority as Division);

• Add - is then next;

• Subtract - (same priority as Addition).

This is known as BIDMAS (taking the first letter of each operation); sometimes it is also known as BODMAS.

When there is a mixture of operations in a calculation, the sequence of operations must be carried out in BIDMAS order.