Number System – Speed Tricks & Tough Problems
Master number properties and shortcut tricks for fast calculation in bank exams.
1. Important Concepts
- Natural Numbers: 1, 2, 3...
- Whole Numbers: 0, 1, 2...
- Integers: ..., -2, -1, 0, 1, 2...
- Prime Numbers: 2, 3, 5, 7...
- Even/Odd Numbers
2. Speed Tricks
- Divisibility Rules (2,3,5,9,11)
- LCM & HCF shortcuts
- Use factorization method
- Last digit concept for powers
3. Tough Problems
Q1: Find the unit digit of 7^45
Solution:
7, 9, 3, 1 (cycle of 4)
45 ÷ 4 → remainder = 1
Answer = 7
Q2: Find LCM of 12, 18, 24
Solution:
12 = 2² × 3
18 = 2 × 3²
24 = 2³ × 3
LCM = 2³ × 3² = 72
Q3: Find HCF of 36 and 48
Solution:
36 = 2² × 3²
48 = 2⁴ × 3
HCF = 2² × 3 = 12
Q4: Which number is divisible by 9? 2345 or 2346
Solution:
Sum of digits:
2345 → 14 (not divisible)
2346 → 15 (not divisible)
Correct answer: None
Q5: Find remainder when 17² is divided by 5
Solution:
17 mod 5 = 2
2² = 4
Answer = 4
4. Exam Tips
- Remember divisibility shortcuts
- Practice unit digit questions
- Use factorization for LCM/HCF
- Save time using patterns
- Back to Practice Library
Shaktimatha Learning
Quant • Number System • Bank Exam Preparation
Quant • Number System • Bank Exam Preparation
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