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Gyaan Maths
CBSE · Class 6-10
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CBSE Maths · Class 6

Chapter 3: Playing with Numbers

Name: ________________________
Date: ______________
Marks: ____ / 10

Factors and multiples; prime and composite numbers; divisibility rules; HCF and LCM.

Questions

  1. Prime factorisation of 180180.
  2. Find HCF of 1818 and 4848 by prime factorisation.
  3. Find LCM of 6,8,126, 8, 12.
  4. Prime factorisation of 8484.
  5. HCF of 2424 and 3636 by prime factorisation.
  6. LCM of 88 and 1212.
  7. Is 9191 prime?
  8. Divisibility by 99 check: 234234.
  9. Find smallest number divisible by 6,8,106, 8, 10.
  10. Verify HCF×\timesLCM =a×b= a\times b for a=12,b=18a=12, b=18.

Extra Practice (Optional)

  • Is 22 the only even prime?
  • Two consecutive primes with difference 22 are called …\ldots?
  • Check if 63216321 is divisible by 1111.

Answer Key (For Teachers)

  1. Answer: 22⋅32⋅52^2\cdot 3^2\cdot 5.
    Working: 180=22⋅32⋅5180 = 2^2\cdot 3^2\cdot 5.
  2. Answer: 66.
    Working: 18=2⋅32,  48=24⋅318 = 2\cdot 3^2,\; 48 = 2^4\cdot 3. → HCF=2⋅3=6\text{HCF} = 2\cdot 3 = 6.
  3. Answer: 2424.
    Working: 6=2⋅3,  8=23,  12=22⋅36 = 2\cdot 3,\; 8 = 2^3,\; 12 = 2^2\cdot 3. → LCM =23⋅3= 2^3\cdot 3.
  4. Answer: 22×3×72^2 \times 3 \times 7
    Working: 84=2×42=2×2×21=22×3×784 = 2\times 42 = 2\times 2\times 21 = 2^2\times 3\times 7.
  5. Answer: 1212
    Working: 24=23×324 = 2^3\times 3, 36=22×3236 = 2^2\times 3^2. HCF =22×3= 2^2\times 3.
  6. Answer: 2424
    Working: 8=23,12=22×38 = 2^3, 12 = 2^2\times 3. LCM =23×3=24= 2^3\times 3 = 24.
  7. Answer: No, composite.
    Working: 91=7×1391 = 7\times 13.
  8. Answer: Yes.
    Working: Digit sum 2+3+4=92+3+4 = 9; divisible.
  9. Answer: 120120
    Working: LCM(6,8,10)=120(6,8,10) = 120.
  10. Answer: Verified.
    Working: HCF =6=6, LCM =36=36; 6×36=216=12×186\times 36 = 216 = 12\times 18.
Gyaan Maths · CBSE Class 6 · Chapter 3
Gyaan Maths — CBSE Class 6-10, built for board-toppers.
v1.1 · Feb 2026