Relatively Prime Numbers

Definition of Relatively Prime Numbers

Two integers a and b are said to be relatively prime if they do not have any common factor other than 1 or - 1.

More about Relatively Prime Numbers

  • Relatively prime numbers are also called as co-primes.

Example of Relatively Prime Numbers

    12 and 13 are relatively prime numbers as there are no common factors between 12 and 13 other than 1.

Video Examples: What are Relatively Prime Numbers?


Solved Example on Relatively Prime Numbers

Ques: Choose the pair of relatively prime numbers in the following.

    Choices:
    A. (7, 14)
    B. (8, 16)
    C. (6, 13)
    D. (6, 12)
    Correct Answer: C

Solution:

    Step 1: Two numbers are said to be relatively prime if their common factor is only 1
    Step 2: Common factors of 6 and 12 are 1, 2, 3, 6
    Step 3: Common factors of 7 and 14 are 1, 7
    Step 4: Common factors of 8 and 16 are 1, 2, 4, 8
    Step 5: Common factor of 6 and 13 is only 1
    Step 6: (6, 13) is a pair of relatively prime numbers.

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