1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Combination question

  1. May 7, 2006 #1
    Hello!

    There's a combination exercise that has been bewildering me for some time now: how many divisors does the number 378 have?

    I know it can be done like this: 378=2x3x3x3x7.
    Divisors are as follows: 1,2,3,6,7,9,12,14,18,21,42,54,63,126,189,378. 16 all together.

    But, in essence, it has to be a combinations task, the only catch is that the element 3 is recurrent.

    Is there a formula that takes this aspect into account?

    MarekS
     
  2. jcsd
  3. May 7, 2006 #2
    Lets say you have three "pools" amongst which you can draw your factors. Let one contain 2^0 and 2^1; one 3^0, 3^1, 3^2, and 3^3; and the last 7^0 and 7^1. Each distinct divisor is made by choosing one number from each pool. So it can easily be seen that the number of total divisors is 2 * 4 * 2 = 16.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Combination question
Loading...