find how many 4 digits no. is less then 1239 such that all 4 digits are distinct.

• ans is 69
  
  case 1- 1000-1099- there are 56 distinct digits
  case 2- 1200-1209- there are 7 distinct digits
  case 3- 1230-1239(excluding 1239)- there are 6 distinct digits
  
  hence, 56+7+6=69ans
• 9 years agoHelpfull: Yes(29) No(2)
• case 1- 10xx- 1*1*8*7=56
  case 2- 120x-1*1*1*7=7
  case 3- 123x-1*1*1*6=6
  69
• 8 years agoHelpfull: Yes(13) No(0)
• 71
  
  make three cases-
  
  case 1-10XX type
  total numbers of distinct 1*1*8*7=56
  
  case 2-120X type
  total numbers of distinct 1*1*1*6=6
  
  case 3-123X type
  total numbers of distinct 1*1*1*9=9
  
  so answer=56+6+9=71
  
• 9 years agoHelpfull: Yes(8) No(44)
• make three cases-
  
  case 1-10XX type
  total numbers of distinct 1*1*8*7=56
  
  case 2-120X type
  total numbers of distinct 1*1*1*7=7
  
  case 3-123X type
  total numbers of distinct 1*1*1*6(bcoz we have used 1,2,3)=6
  total = 56+7+6= 69
  
• 8 years agoHelpfull: Yes(6) No(1)
• ans : 5 numbers
  
  no. will be of form 123x where x=4,5,6,7,8 as digits are distinct.
• 9 years agoHelpfull: Yes(5) No(21)
• 
  
  case 1- 1000-1099- there are 56 distinct digits
  case 2- 1200-1209- there are 7 distinct digits
  case 3- 1230-1239(excluding 1239)- there are 6 distinct digits
  
  hence, 56+7+6=69ans
  
• 8 years agoHelpfull: Yes(4) No(0)
• ans is 68
  from 1000 to 1100 there are 8*7=56 distinct 4 digit numbers
  from 1101 to 1200 there are no distinct 4 digit numbers
  from 1201 to 1238 there 12 distinct 4 digit numbers
  so total is 56+12=68
• 9 years agoHelpfull: Yes(3) No(4)
• there are numbers such as 1023,1024,1025,1026,1027,1028,1029,and so on should also taken into consideration so answer cannot be 5. now tell me the exact procedure to solve this kind of questions........
• 9 years agoHelpfull: Yes(2) No(1)
• how aman vikram sing's answer can be marked as the best answer .......... ans will be 69 ........... so please before marking check the answer correctly -_-
• 8 years agoHelpfull: Yes(2) No(0)