Chapter 5: Prime Time
Kuch numbers kai tarah se barabar groups mein baante ja sakte hain; kuch bilkul nahi bant-te. Is chapter mein hum multiples aur factors se khelenge, prime numbers se milenge (saare numbers ke building blocks), divisibility jaanchne ki jaldi wali tarkeebein seekhenge, aur aisi paheliyon par khatam karenge jo abhi tak koi nahi suljha paaya.
Is chapter mein tum
- common multiples aur common factors dhoondhna
- prime aur composite numbers pahchaanna, aur chhalni se primes dhoondhna
- co-prime numbers pahchaanna aur numbers ko prime factors mein todna
- bina bhaag diye 2, 4, 5, 8 aur 10 se divisibility jaanchna
Topics
- Common Multiples aur Common Factors NCERT 5.1
Multiples: jumps mein gino (4, 8, 12 …). Factors: jo poora bhaag dein (12 ke factors: 1, 2, 3, 4, 6, 12).
- Prime Numbers NCERT 5.2
Prime: theek do factors (1 aur khud). Composite: do se zyada. 1 dono nahi.
- Co-prime Numbers NCERT 5.3
Co-prime: ikloota common factor 1. Prime hona zaroori nahi (8 aur 15).
- Prime Factorisation NCERT 5.4
Prime factorisation: number ko sirf primes ke guna se likho (60 = 2 × 2 × 3 × 5).
- Divisibility Tests NCERT 5.5
10: aakhri digit 0. 5: aakhri digit 0 ya 5. 2: aakhri digit even.
- Numbers ke saath maza NCERT 5.6
Twin primes ka antar 2 hota hai (11 aur 13).
Key words
- Multiple
- kisi number ke jumps mein ginne se milne wale numbers (3, 6, 9 …)
- Factor
- jo number doosre ko poora bhaag de
- Prime number
- jiske theek do factors hon, 1 aur khud
- Composite number
- jiske do se zyada factors hon
- Co-prime
- do numbers jinka ikloota common factor 1 ho
- Prime factorisation
- number ko sirf primes ke guna se likhna
Summary
- Common multiples dono numbers ki multiple lists mein hote hain; common factors dono factor lists mein.
- Prime ke theek do factors hote hain; composite ke zyada; 1 dono nahi. 2 akela even prime hai.
- Co-prime numbers ka 1 ke alawa koi factor saajha nahi, chahe dono mein se koi prime na ho.
- Har composite number primes ka guna ek hi tarah se hai (order chhodkar).
- Divisibility aakhri digits se jaanchi ja sakti hai: 2, 5 aur 10 ke liye ek digit, 4 ke liye do, 8 ke liye teen.