BIDMAS — Definition, Formula & Examples
BIDMAS is a mnemonic used mainly in the UK to remember the order of operations: Brackets, Indices, Division, Multiplication, Addition, Subtraction. It tells you the sequence in which to evaluate parts of a mathematical expression.
BIDMAS is an acronym encoding the conventional precedence hierarchy for arithmetic operations: parenthetical groupings (Brackets) are evaluated first, followed by exponentiation (Indices), then Division and Multiplication (performed left to right at equal precedence), and finally Addition and Subtraction (also performed left to right at equal precedence).
How It Works
When you encounter an expression with multiple operations, work through them in BIDMAS order. First, simplify anything inside brackets. Next, evaluate indices (powers and roots). Then handle division and multiplication from left to right — neither one outranks the other. Finally, perform addition and subtraction from left to right. BIDMAS is mathematically identical to PEMDAS, BODMAS, and BEDMAS; the different letters simply reflect regional vocabulary choices.
Worked Example
Problem: Evaluate .
Brackets: Inside the brackets, apply Indices first: . Then subtract: .
Multiplication: Multiply before adding.
Addition: Add the remaining terms.
Answer:
Why It Matters
BIDMAS is the standard term taught in UK and Australian maths curricula. Understanding it ensures you can correctly interpret any arithmetic or algebraic expression, which is essential for GCSE maths and every science or engineering course that follows.
Common Mistakes
Mistake: Assuming Division always comes before Multiplication because D appears before M in the acronym.
Correction: Division and Multiplication share the same precedence level. Evaluate them left to right in the order they appear. The same applies to Addition and Subtraction.