Understanding BIDMAS Order of Operations

May 3, 2025

Lecture on BIDMAS (Order of Operations)

Introduction

  • Focus: Understanding BIDMAS, the order of operations
  • Goal: Gain confidence in BIDMAS calculations to progress to formulas
  • Note: Not to be confused with Christmas (order of opening presents)

What is BIDMAS?

  • BIDMAS stands for:
    • B - Brackets
    • I - Indices (powers and roots)
    • D - Division
    • M - Multiplication
    • A - Addition
    • S - Subtraction

Importance of BIDMAS

  • Ensures correct calculation order
  • Example miscalculation: 20 + 10 * 2 with incorrect mental math might yield 60, while correct order gives 40
    • Smartphones follow BIDMAS, hence correct results

Breakdown of BIDMAS

  1. Brackets: Solve expressions within brackets first
  2. Indices: Follow brackets; includes powers (e.g., squared, cubed)
  3. Division and Multiplication: Handle as they appear from left to right
  4. Addition and Subtraction: Handle as they appear from left to right

Example Calculations

  • Expression: 5 + (6 * 2^2) + 7

    • Step 1: Solve indices first: 2^2 = 4
    • Step 2: Within brackets, multiply: 6 * 4 = 24
    • Step 3: Add within brackets: 24 + 7 = 31
    • Step 4: Add result to 5: 5 + 31 = 36

  • Expression: 3 + 16 * 2

    • Step 1: Multiply 16 * 2 = 32
    • Step 2: Add: 3 + 32 = 35

  • Expression: 16 * (2 + 3)

    • Step 1: Solve within brackets: 2 + 3 = 5
    • Step 2: Multiply: 16 * 5 = 80

Additional Practice

  • Expression: 3 * 2 + 8 / 4

    • Solve in any order for multiplication/division first
    • Multiply: 3 * 2 = 6
    • Divide: 8 / 4 = 2
    • Add results: 6 + 2 = 8

  • Expression: 3 + 42 / 7

    • Divide first: 42 / 7 = 6
    • Add: 3 + 6 = 9

True or False Practice

  • 12 / 4 + 3 = 6: True
    • Divide: 12 / 4 = 3
    • Add: 3 + 3 = 6
  • 12 / 3 + 3 = 2: False, answer is 7
    • Divide: 12 / 3 = 4
    • Add: 4 + 3 = 7
  • 4 + 2 * 4^2 = 96: False, answer is 36
    • Indices: 4^2 = 16
    • Multiply: 2 * 16 = 32
    • Add: 4 + 32 = 36

Application

  • Using BIDMAS for complex formulas involving:
    • Area
    • Volume
    • Surface area of geometric shapes (e.g., cylinders)
    • Note on Pythagoras Theorem being irrelevant to functional skills

Conclusion

  • BIDMAS is crucial for correctly solving mathematical expressions and formulas.
  • Next session will focus on applying BIDMAS to formulas.

Full transcript