How many positive integers less than 450 can be formed using 1,2,5 and 6 for it's digits, with each digit being used only once?

• Ans: 28
  Num of possible 1 digit numbers = 4
  Num of possible 2 digit numbers = 4*3 = 12
  For 3 digit numbers, to meet the condition
  the number should be less than 450, 5 and 6 cannot be in the hundredth
  position.
  Num of possible 3 digit numbers = 2*3*2 = 12
  Total +ve integers meeting the condition = 4+12+12 = 28
• 11 years agoHelpfull: Yes(62) No(6)
• yes it will be 28 numbers.... i made a mistake...
• 11 years agoHelpfull: Yes(8) No(3)
• three digit no=2*3*2=12
  two digit no=4*3=12
  one digit no=4
  so, total nos= 12+12+4=28 ANS
• 11 years agoHelpfull: Yes(4) No(0)
• 12 such integers are possible
• 11 years agoHelpfull: Yes(2) No(7)
• guys will u plz xplain me why is it 2*3*2 for 3digit no.?
• 10 years agoHelpfull: Yes(2) No(1)
• @ Prakash: Yes,Many made the same mistake in a test,including me!
• 11 years agoHelpfull: Yes(1) No(1)
• @karthika- yup!! we get the perception that a 3 digit no less than 450 is required..
  
• 11 years agoHelpfull: Yes(1) No(1)
• no of integers should be 28.
  1 digit no's=4
  2 digit no's be=4*3=12
  3 digit no's be=2*3*2=12
• 11 years agoHelpfull: Yes(1) No(0)
• Yeah! yu r ryt :D
• 11 years agoHelpfull: Yes(0) No(1)
• 16+4+12=32
• 11 years agoHelpfull: Yes(0) No(9)
• 1 digit number = 4
  2 digit number = 4*3 =12
  3 digit number< 450 =2*3*2=12
  adding three =28
• 11 years agoHelpfull: Yes(0) No(0)
• can anyone explain . Num of possible 2 digit numbers = 4*3 = 12
  
  where does the 3 come from ? and what is it?
• 10 years agoHelpfull: Yes(0) No(0)