Q. How many 9 digit number can be formed from 1,2,3,4,5 which is divisible by 4,repetition is allowed?

• digits are 1,2,3,4,5
  for a no. to be divisible by 4, last two digit should be divisible by 4
  
  last two digit may be 12,24,32,44,52 (5 ways)
  last two places can be filled in 5 ways
  so, remaining 7 places, each place can be filled in 5 ways => 5^7 ways
  
  total no. formed = 5 * 5^7 = 5^8
• 10 years agoHelpfull: Yes(54) No(0)
• @rakesh ur genius
• 10 years agoHelpfull: Yes(15) No(2)
• rakesh bhai hats off
  
• 9 years agoHelpfull: Yes(2) No(2)
• Ans:
  2*5^8
  because 8th place can be filled with the digits 1 2 3 4 5 so this can also be filled in 5 ways but the 9th place can be filled in 2 ways because only 2 and 4 comes there hence ans will be 2*(5^8)
• 9 years agoHelpfull: Yes(1) No(4)
• 5^7(3+2)=5^8
• 9 years agoHelpfull: Yes(0) No(1)
• as we consider last two digits of the no. to check the divisibility by 4.. so last two digits can be filled as:
  12
  24
  32
  44
  52
  so,here last digit can only be filled by 2 ways i.e. 2 & 4 while
  second last digit can be filled by 5 ways i.e. 1,2,3,4,5
  and other first 7 places can be filled in 5^7 ways as repeation is allowed.
  so required result is: 5^7*5*2= 5^8*2.
• 9 years agoHelpfull: Yes(0) No(0)
• For divisible by 4 we will see last 2 digits should be divisible by 4
  we have 5 such no
  so (5^7)* 5
• 7 years agoHelpfull: Yes(0) No(0)