Notices
Results 1 to 1 of 1

Thread: Are 5 and 20 relatively prime with each other?

  1. #1 Are 5 and 20 relatively prime with each other? 
    New Member
    Join Date
    Aug 2018
    Posts
    1
    Hi all, quick question regarding relatively prime numbers.

    Factors of 5: 1, 5
    Factors of 20: 1, 2, 4, 5, 10, 20
    Greatest common factor = 5

    Since the greatest common factor of both numbers is 5, does that mean these numbers are not relatively prime towards each other? Or does 5 not count as a factor since it is one of the numbers I am checking?

    Thanks!


    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Freshman
    Join Date
    Aug 2018
    Posts
    43
    Two numbers are relatively prime if they have no factors in common other than 1. So those two numbers are not relatively prime - because of the common 5, which does count as a factor.


    Reply With Quote  
     

  4. #3  
    Forum Isotope
    Join Date
    Feb 2012
    Location
    Western US
    Posts
    2,794
    Quote Originally Posted by southp4w View Post
    Hi all, quick question regarding relatively prime numbers.

    Factors of 5: 1, 5
    Factors of 20: 1, 2, 4, 5, 10, 20
    Greatest common factor = 5

    Since the greatest common factor of both numbers is 5, does that mean these numbers are not relatively prime towards each other? Or does 5 not count as a factor since it is one of the numbers I am checking?

    Thanks!
    By definition, no, they are not relatively prime.

    The test is easy:

    If the largest common prime factor exceeds 1, they are not relatively prime. That's it.

    Here, 5 exceeds 1, even for extremely large values of 1.
    Reply With Quote  
     

Similar Threads

  1. Prime Obsession.
    By Dave Wilson in forum Mathematics
    Replies: 2
    Last Post: October 29th, 2013, 03:54 PM
  2. Prime Fraction
    By TimeSpaceLightForce in forum Mathematics
    Replies: 11
    Last Post: November 25th, 2012, 02:59 PM
  3. Prime
    By MrYang in forum Mathematics
    Replies: 2
    Last Post: January 11th, 2009, 04:06 PM
  4. pi and prime
    By parag1973 in forum Mathematics
    Replies: 7
    Last Post: August 31st, 2008, 09:01 AM
  5. not prime
    By siegfried in forum Mathematics
    Replies: 7
    Last Post: August 21st, 2008, 08:40 AM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •