What will be obtained if 8 is subtracted from the H.C.F. of 168, 189 and 231 ?

2024

What will be obtained if 8 is subtracted from the H.C.F. of 168, 189 and 231 ?

  1. A.

    15

  2. B.

    10

  3. C.

    21

  4. D.

    None of these

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Correct answer: D

To find the final result, we need to first calculate the Highest Common Factor (H.C.F.) of 168, 189, and 231, and then subtract 8 from that value.

Step-by-Step Calculation

1. Find the H.C.F. of 168, 189, and 231: We can find the H.C.F. by prime factorization or by finding the differences between the numbers.

  • Prime Factorization:

    • 168 = 2 × 84 = 2² × 42 = 2³ × 21 = 2³ × 3 × 7

    • 189 = 3 × 63 = 3² × 21 = 3³ × 7

    • 231 = 3 × 77 = 3 × 7 × 11

  • Identify Common Factors:

    • The only prime factor common to all three numbers (168, 189, and 231) is 3 and 7.

    • H.C.F. = 3 × 7 = 21.

2. Subtract 8 from the H.C.F.:

  • H.C.F. = 21

  • Result = 21 - 8 = 13.

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