Class 8 Maths – Chapter 16: Playing with Numbers
Step 10: Word Problems & Important Exam Questions
This step helps students to apply concepts of divisibility, LCM and HCF in real exam situations.
🔹 A. Very Short Answer Questions (VSA)
Q1. Find the smallest number divisible by 12, 15 and 18.
Answer:
LCM of 12, 15 and 18 = 180
So, the smallest number is 180.
Q2. What is the HCF of 45 and 60?
Answer:
HCF of 45 and 60 = 15
🔹 B. Short Answer Questions (SA)
Q3. Find the largest number that divides 84 and 120 leaving remainder 6 in each case.
Solution:
84 − 6 = 78
120 − 6 = 114
Required number = HCF of 78 and 114
78 = 2 × 3 × 13
114 = 2 × 3 × 19
HCF = 6
🔹 C. Long Answer Questions (LA)
Q4. Find the two numbers whose HCF is 12 and LCM is 180.
Solution:
HCF × LCM = Product of numbers
12 × 180 = 2160
Let the numbers be 12x and 12y (x and y are co-prime)
12x × 12y = 2160
x × y = 2160 ÷ 144 = 15
Co-prime factors of 15 → 3 and 5
Numbers = 12 × 3 = 36 and 12 × 5 = 60
✍️ Examiner-Friendly Writing Tips
- Write formulas clearly
- Show all steps
- Underline final answers
- Use neat calculations
🧠Chapter Memory Recap
- Divisibility rules → Quick checks
- LCM → Smallest multiple
- HCF → Greatest divisor
- LCM × HCF = Product of numbers
🎯 Chapter 16 completed successfully!
📘 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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