What are the Highest common factor and Lowest common multiple of 6, 72, 120 ?

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What are the Highest common factor and Lowest common multiple of 6, 72, 120 ?

  1. A.

    12, 180

  2. B.

    6, 360

  3. C.

    360, 6

  4. D.

    12, 360

Attempted by 143 students.

Show answer & explanation

Correct answer: B

Method: factor each number into primes; HCF is the product of common primes with the smallest exponents, and LCM is the product of all primes with the largest exponents.

  • 6 = 2 × 3

  • 72 = 2 × 2 × 2 × 3 × 3 ( = 2^3 × 3^2 )

  • 120 = 2 × 2 × 2 × 3 × 5 ( = 2^3 × 3 × 5 )

HCF calculation: common primes are 2 and 3 with minimum exponents 1 and 1 → HCF = 2 × 3 = 6

LCM calculation: take the highest exponents for each prime: 2^3, 3^2, 5^1 → LCM = 2 × 2 × 2 × 3 × 3 × 5 = 360

Final answer: HCF = 6, LCM = 360

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