Results 1 to 3 of 3

Math Help - divisibility problem

  1. #1
    Member
    Joined
    Nov 2009
    Posts
    80

    divisibility problem

    How many different positive integers less than 1000 are divisible by 7 but not 11?

    how do i do this without explicitly checking each multiple of 7 or 11 less than 1000?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,614
    Thanks
    1581
    Awards
    1
    Quote Originally Posted by jmedsy View Post
    How many different positive integers less than 1000 are divisible by 7 but not 11?

    how do i do this without explicitly checking each multiple of 7 or 11 less than 1000?
    Use the floor function: \left\lfloor {\frac{{1000}}{7}} \right\rfloor  - \left\lfloor {\frac{{1000}}{{77}}} \right\rfloor .
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Nov 2009
    Posts
    80
    Quote Originally Posted by Plato View Post
    Use the floor function: \left\lfloor {\frac{{1000}}{7}} \right\rfloor  - \left\lfloor {\frac{{1000}}{{77}}} \right\rfloor .
    thanks, i just came up with that
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. A divisibility problem
    Posted in the Number Theory Forum
    Replies: 6
    Last Post: August 19th 2010, 08:21 PM
  2. A divisibility problem 2
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: February 27th 2010, 04:32 PM
  3. A divisibility problem 3
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: February 27th 2010, 04:15 PM
  4. Divisibility problem
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: January 28th 2010, 02:42 PM
  5. GCD divisibility problem
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: May 4th 2009, 01:14 AM

Search Tags


/mathhelpforum @mathhelpforum