Class 6 · Chapter 5
Prime Time
Factors, multiples, primes, composites, HCF and LCM.
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Ganita Prakash · Class 6 (2026-27)
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Detailed theory
Two factors only: and itself. First primes: . Only even prime is . Sieve of Eratosthenes lists primes up to .
Key concepts & formulas
01
**Factor**: divides a number exactly; **multiple**: contains a number as a factor.
02
**Prime**: exactly 2 factors; **composite**: more than 2 factors.
03
is neither prime nor composite.
04
**HCF** = largest common factor. **LCM** = smallest common multiple.
05
HCF × LCM = product of the two numbers.