Number System: Types, Place Value & Primes

A high-yield practice drill on the foundational number system for Kerala PSC examinations (LDC, LGS, CPO, Fireman, Secretariat Assistant Prelims). It provides systematic practice on natural numbers, whole numbers, integers, place value vs face value, prime and composite numbers up to 100, and twin primes.

Study Scope

• Classification of Numbers: Natural ($$\mathbb{N}$$), Whole ($$\mathbb{W}$$), Integers ($$\mathbb{Z}$$), and Rational numbers
• Place Value and Face Value: Calculating place values and differences with face values
• Prime Numbers: Definition, smallest prime ($$2$$), the only even prime ($$2$$), primes between $$1$$ and $$100$$ ($$25$$ primes)
• Twin Primes: Prime pairs differing by $$2$$ (e.g. $$3, 5$$; $$5, 7$$; $$11, 13$$)
• Composite Numbers: Smallest composite ($$4$$), identifying composites like $$91 = 7 \times 13$$

Tested Competencies

• Distinguish between place value (positional) and face value (intrinsic)
• Quickly identify prime and composite numbers in exam questions
• Eliminate traps regarding the unique status of $$1$$ and $$2$$