Class 8 Maths – Chapter 16: Playing with Numbers
Step 8: Relationship between LCM and HCF
There is a very important relationship between LCM and HCF of two numbers.
🔹 Formula
LCM × HCF = Product of the two numbers
📘 Example 1
Find the LCM of two numbers if their HCF = 12 and product = 864.
Solution:
LCM × HCF = Product of numbers
LCM × 12 = 864
LCM = 864 ÷ 12 = 72
📘 Example 2
If two numbers are 18 and 30, verify the relationship.
HCF of 18 and 30 = 6
LCM of 18 and 30 = 90
LCM × HCF = 90 × 6 = 540
Product of numbers = 18 × 30 = 540
Hence, verified.
📝 Exam Writing Tips
- Always write the formula clearly
- Substitute values step-by-step
- Underline the final answer
🧠 Memory Trick
LCM above ⬆️
HCF below ⬇️
Middle is Product 🔁
Key Point: This formula works only for two numbers.
📘 Class 8 Mathematics – Complete Library
CBSE | NCERT | State Syllabus
Chapter 1: Rational Numbers
Chapter 2: Linear Equations in One Variable
Chapter 3: Understanding Quadrilaterals
Chapter 4: Practical Geometry
Chapter 5: Data Handling
Chapter 6: Squares and Square Roots
Chapter 7: Cubes and Cube Roots
- NCERT Notes
- MCQs
- Worksheet
- Worksheet Answers
- Mind Map & Easy Tricks
- Important Exam Questions
- Very Important Questions
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