Adding, Subtracting, Multiplying and Dividing are operators: they perform actions on numbers. Numbers may also have indices - these control operations such as squaring and square rooting. Brackets () are used to control the order in which calculations take place.
Each operation has a priority:
• Brackets are always calculated first;
• Indices - such as 32 - are calculated next;
• Divide - is next;
• Multipy (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.
1. Ellie has calculated 4 + 6 ÷ 2 = 5. Is she correct?
BIDMAS: Do the division first: 6 ÷ 2 = 3, then the addition 4 + 3 = 7.
2. Put in brackets to make this calculation correct: 3 + 42 = 49
Answer: (3 + 4)2 = 49
Put brackets before the 3, and between the 4 and 2.