How many 9 digit numbers are possible by using the digits 1,2,3,4,5 which are divisible by 4 if the repetition is allowed?
a)5^7 b)5^6 c)5^9 d)5^8

• 5^8
  as there are 5 ways to fill last two positions (12,24,32,44,52)
  also repetition is allowed, hence remaining 7 positions can be filled in 5^7 ways
  totl ways to form 9 digit no. divisible by 4= 5*5^7=5^8
• 13 years agoHelpfull: Yes(4) No(0)
• shortcut method for such questions..
  5^(n-1)
• 13 years agoHelpfull: Yes(1) No(1)
• 8^5
  as there are 5 ways to fill last two positions (12,24,32,44,52)
  also repetition is allowed, hence remaining 7 positions can be filled in 7^5 ways
  totl ways to form 9 digit no. divisible by 4 = 7^5*5=8^5
• 13 years agoHelpfull: Yes(0) No(6)