Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Combinations & Permutations

  1. Apr 27, 2005 #1
    I had mono while this unit was being taught so im havin quite a lot of trouble figurin this homework out. Like this question:

    How many 6 digit numbers greater than 800 000 can be made from the digits 1, 1, 5, 5, 5, 8?

    I have absolutly no idea so any help would be appriciated! Thanks!
  2. jcsd
  3. Apr 27, 2005 #2


    User Avatar
    Science Advisor

    Because numbers must be greater than (800,000), the first digit must be 8. The number of different arrangements of the remaining 5 digits, consisting of 2-(1)'s and 3-(5)'s is given by:
    {Number Arrangements} = (5!)/{(2!)*(3!)} = (10)

    Last edited: Apr 27, 2005
  4. Apr 27, 2005 #3
    ah ok i was tryin something like that, but i didnt realize brackets were necessary. Thankyou!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook