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I need to find how many four digit numbers can be made using exactly 2 different digits. ALL DIGITS FROM 1 TO 9 CAN BE USED. NOT JUST 1 AND 0

  • 0
    Are leading zeros allowed, as in `0220`?2012-11-20
  • 0
    yes zeroes can be the starting digit2012-11-20
  • 1
    I think you mean all digits from 0 (not $1$) to $9$. And you don't need to shout.2012-11-20
  • 5
    You should make some effort yourself. Having people feed you answers here before you've even engaged your brain will not help you learn anything.2012-11-20

4 Answers 4