how many numbers consisting of 5 digits can be formed which the digits 3 , 4 , 7 are used are used only once and the digit 5 is used twice

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  • -29
5!/2! . Since exchanging the two 5s gives no change in number.
 
  • 8
It's 5!/2!. 2! because it has 2 5's.
  • 2
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