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Railways PYQCBT 2 2017

RRB NTPC · Question 1

Find out which of the following sets form co-prime numbers.

  1. (12, 7)

  2. (21, 42)

  3. (3, 9)

  4. (43, 129)

Show answer & explanation

Answer: (A) (12, 7)

Explanation

Co-prime numbers have HCF 1. HCF(12, 7) = 1, while 21 and 42 share 21, 3 and 9 share 3, and 43 and 129 share 43 (129 = 3 × 43).