SSC GD CH 01
# 1. CH 01 : NUMBER SYSTEM 🔢 1. Types of Numbers Type Examples Description Natural Numbers 1, 2, 3, 4, 5… Counting numbers starting from 1 Whole Numbers 0, 1, 2, 3… Natural numbers + 0 Integers …–3, –2, –1, 0, 1… Positive & negative whole numbers Rational Numbers 1/2, –3/4, 5 Can be written in form p/q, q ≠ 0 Irrational Numbers √2, √3, Ï€ Cannot be written as p/q; non-terminating Real Numbers All rational & irrational Includes all the above 🧮 2. Even and Odd Numbers Even Numbers: Divisible by 2 → 2, 4, 6, 8… Odd Numbers: Not divisible by 2 → 1, 3, 5, 7… 🔢 3. Prime and Composite Numbers Prime Numbers: Only 2 factors → 2, 3, 5, 7… Composite Numbers: More than 2 factors → 4, 6, 8, 9… Important: 2 is the only even prime number 1 is neither prime nor composite 🔄 4. LCM and HCF LCM (Lowest Common Multiple): Smallest number divisible by all given numbers HCF (Highest Common Factor): Largest number that divides all given numbers ...