five different digits 7,3,6,2,5. out of these digits 4 digit numbers are formed .find that which have atleast one digit repeated

• total no numbers formed using the digits(with repetition)
  ist palce=5 ways
  2nd place=5 ways
  3rd palce= 5 ways
  4th palce=5 ways
  :total ways=5^4=625.
  considering the case when no two digits are repeated
  ist place =5 ways
  2nd place= 4ways
  3 place= 3 ways
  4th palce=2 ways.
  :so total ways in which no two digits are repeated=5x4x3x2=120
  
  a/q
  total no of digits in which at least there is one repetition=625-120=505.
• 11 years agoHelpfull: Yes(30) No(4)
• condition for atleast one digit repeated
  (all digits repeated)-(no digits repeated)
  5^4-5!
  625-120=505
• 11 years agoHelpfull: Yes(8) No(0)