SOLUTION: From the numbers 1,2,3,4,5,6,7,8, and 9, four different numbers are selected to form a four-digit number. A. How many four-digit numbers can be formed?

Question 1173259: From the numbers 1,2,3,4,5,6,7,8, and 9, four different numbers are selected to form a four-digit number.
A. How many four-digit numbers can be formed?
Answer by ikleyn(52778) (Show Source): You can put this solution on YOUR website!
.


If repeating is allowed, the answer is  9*9*9*9 =  = 6561  possible numbers.


If repeating is not allowed, then the answer is 9*8*7*6 = 3024 possible numbers.

Solved // answered.

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If you want to see many similar solved problems on PERMUTATIONS, see my lessons
    - Introduction to Permutations
    - PROOF of the formula on the number of Permutations
    - Simple and simplest problems on permutations
    - Special type permutations problems
    - Problems on Permutations with restrictions
    - OVERVIEW of lessons on Permutations and Combinations
in this site.

Also, you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic "Combinatorics: Combinations and permutations".

Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.

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